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营销科学学报
2012年 21卷 1期
刊出日期：20120719
GENERAL
60201
Fractional backward Kolmogorov equations
张红, 李国华, 罗懋康
This paper derives the fractional backward Kolmogorov equations in fractal spacetime based on the construction of a model for dynamic trajectories. It shows that for the type of fractional backward Kolmogorov equation in the fractal time whose coefficient functions are independent of time, its solution is equal to the transfer probability density function of the subordinated process
X
(
S
_{α}
(
t
)), the subordinator
S
_{α}
(
t
) is termed as the inversetime αstable subordinator and the process
X
(
τ
) satisfies the corresponding time homogeneous Itô stochastic differential equation.
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60202
Estimation of key rate after setting dead time
刘东, 银振强, 王双, 王粉梅, 陈巍, 韩正甫
The estimation of key rate is an important aspect of the quantum key distribution process, especially in the use of dead time. In this paper, we demonstrate a numerical simulation to estimate the average detection probability and the key rate. Using our method, the estimated average detection probability is better than the previous result. Besides, we can easily find the best dead time, especially when considering the impact of after pulse.
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60203
Oscillatory and antioscillatory motifs in genetic regulatory networks
叶纬明, 张朝阳, 吕彬彬, 狄增如, 胡岗
Recently, selfsustained oscillatory genetic regulatory networks (GRNs) have attracted significant attention in the biological field. Given a GRN, it is important to anticipate whether the network could generate oscillation with proper parameters, and what the key ingredients for the oscillation are. In this paper the ranges of some functionrelated parameters which are favorable to sustained oscillations are considered. In particular, some oscillatory motifs appearing with highfrequency in most of the oscillatory GRNs are observed. Moreover, there are some antioscillatory motifs which have a strong oscillation repressing effect. Some conclusions analyzing these motif effects and constructing oscillatory GRNs are provided.
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60301
A density functional theory study on parameters fitting of ultra long armchair (
n, n
) single walled boron nitride nanotubes
王艳丽, 张军平, 苏克和, 王欣, 刘艳, 孙旭
Armchair (
n, n
) single walled boron nitride nanotubes with
n
=217 are studied by the density functional theory at the B3LYP/321G(d) level combined with the periodic boundary conditions for simulating the ultra long model. The results show that the structure parameters and the formation energies bear a strong relationship to
n
. The fitted analytical equations are developed with correlation coefficients larger than 0.999. The energy gaps of (2, 2) and (3, 3) tubes are indirect gaps, and the larger tubes (
n
=417) have direct energy gaps. Results show that the armchair boron nitride nanotubes (
n
=217) are insulators with wide energy gaps of between 5.93 eV and 6.23 eV.
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60302
Quantum dynamic behaviour in a coupled cavities system
彭俊, 邬云文, 李小娟
The dynamic behaviour of the twosite coupled cavities model which is doped with ta wolevel system is investigated. The exact dynamic solutions in the general condition are obtained via Laplace transform. The simple analytical solutions are obtained in several particular cases, which demonstrate the clear and simple physical picture for the quantum state transition of the system. In the large detuning or hoppling case, the quantum states transferring between qubits follow a slow periodic oscillation induced by the very weak excitation of the cavity mode. In the large coupling case, the system can be interpreted as two JaynesCummings model subsystems which interact through photon hop between the two cavities. In the case of
λ
≈
Δ
>>
g
, the quantum states transition of qubits is accompanied by the excitation of the cavity, and the cavity modes have the same dynamic behaviours and the amplitude of probability is equal to 0.25 which does not change with the variation of parameter.
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60303
Security proof of counterfactual quantum cryptography against general interceptresend attacks and its vulnerability
张盛, 王剑, 唐朝京
Counterfactual quantum cryptography, recently proposed by Noh, is featured with no transmission of signal particles. This exhibits evident security advantages, such as its immunity to the wellknown photonnumbersplitting attack. In this paper, the theoretical security of counterfactual quantum cryptography protocol against the general interceptresend attacks is proved by bounding the information of an eavesdropper Eve more tightly than in Yin's proposal [
Phys. Rev
. A
82
042335 (2010)]. It is also shown that practical counterfactual quantum cryptography implementations may be vulnerable when equipped with imperfect apparatuses, by proving that a negative key rate can be achieved when Eve launches a timeshift attack based on imperfect detector efficiency.
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60304
Interactions between bright solitons in different species of Bose—Einstein condensates
颜家壬, 周杰
The dynamics of a brightbright vector soliton in a cigarshaped BoseEinstein condensate trapping in a harmonic potential is studied. The interaction between bright solitons in different species with small separation is derived. Unlike the interaction between solitons of the same species, it is independent of the phase difference between solitons. It may be of attraction or repulsion. In the former case, each soliton will oscillate about and pass through each other around the masscenter of the system, which will also oscillate harmonically due to the harmonic trapping potential.
2012 Vol. 21 (1): 60304060304 [
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60305
Quantum phases of Bose gases on a lattice with pairtunneling
王月明, 梁九卿
We investigate the strongly interacting lattice Bose gases on a lattice with twobody interaction of nearest neighbors characterized by pair tunneling. The excitation spectrum and the depletion of the condensate of lattice Bose gases are investigated using the Bogoliubov transformation method and the results show that there is a pair condensate as well as a single particle condensate. The various possible quantum phases, such as the Mottinsulator phase (MI), the superfluid phase (SF) of an individual atom, the charge density wave phase (CDW), the supersolid phase (SS), the pairsuperfluid (PSF) phase, and the pairsupersolid phase (PSS) are discussed in different parametric regions within our extended BoseHubbard model using perturbation theory.
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60401
Gravitational collapse with standard and dark energy in the teleparallel equivalent of general relativity
Gamal G. L. Nashed
A perfect fluid with selfsimilarity of the second kind is studied within the framework of the teleparallel equivalent of general relativity (TEGR). A spacetime which is not asymptotically flat is derived. The energy conditions of this spacetime are studied. It is shown that after some time the strong energy condition is not enough to satisfy showing a transition from standard matter to dark energy. The singularities of this solution are discussed.
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60402
Gravitational waves from the axial perturbations of hyperon stars
文德华, 燕晶, 刘雪梅
The eigenfrequencies of the axial
w
mode oscillations of hyperon stars are examined. It is shown that as the appearance of hyperons softens the equation of state of the superdensity matter, the frequency of gravitational waves from the axial
w
mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass. Moreover, the eigenfrequencies of hyperon stars also have scaling universality. It is shown that the EURO thirdgeneration gravitationalwave detector has the potential to detect the gravitationalwave signal emitted from the axial
w
mode oscillations of a hyperon star.
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60501
The stability of a nonextensive relativistic Fermi system
王海堂, 门福殿, 何晓刚, 隗群梅
Based on the statistical theory of nonextensive relativity, and using theoretical analysis and numerical simulation, the nonextensive mechanical stability of ultrarelativistic free Fermi gas is investigated. The expressions of the stability conditions under high and low temperatures are given, and the mechanisms of the influences of temperature, ultrarelativistic effect, and nonextensive parameter q on stability are analysed. Our results show that at high temperature and under the condition of
q
<1, the stability of a nonextensive system is weaker than that of an extensive system, and the relativistic effect reduces system stability as compared with a nonrelativistic system. However, under the condition of
q
>1, the stability of the nonextensive system is stronger than that of the extensive system, and the relativistic effect strengthens the system stability as compared with the nonrelativistic system. In addition, under the condition of low temperature, the variation of the stability of the nonextensive system with temperature has a turning point.
2012 Vol. 21 (1): 60501060501 [
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60502
Cryptanalysis on an image block encryption algorithm based on spatiotemporal chaos
王兴元, 何国祥
An image block encryption scheme based on spatiotemporal chaos has been proposed recently. In this paper, we analyse the security weakness of the proposal. The main problem of the original scheme is that the generated keystream remains unchanged for encrypting every image. Based on the flaws, we demonstrate a chosen plaintext attack for revealing the equivalent keys with only 6 pairs of plaintext/ciphertext used. Finally, experimental results show the validity of our attack.
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60503
Oneway hash function construction based on the spatiotemporal chaotic system
罗玉玲, 杜明辉
Based on the spatiotemporal chaotic system, a novel algorithm for constructing a oneway hash function is proposed and analysed. The message is divided into fixed length blocks. Each message block is processed by the hash compression function in parallel. The hash compression is constructed based on the spatiotemporal chaos. In each message block, the ASCII code and its position in the whole message block chain constitute the initial conditions and the key of the hash compression function. The final hash value is generated by further compressing the mixed result of all the hash compression values. Theoretic analyses and numerical simulations show that the proposed algorithm presents high sensitivity to the message and key, good statistical properties, and strong collision resistance.
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60504
Arbitrary fullstate hybrid projective synchronization for chaotic discretetime systems via a scalar signal
Giuseppe Grassi
In this paper we present a new projective synchronization scheme, where two chaotic (hyperchaotic) discretetime systems synchronize for any arbitrary scaling matrix. Specifically, each drive system state synchronizes with a linear combination of response system states. The proposed observerbased approach presents some useful features: i) it enables {exact} synchronization to be achieved in finite time (i.e., {deadbeat} synchronization); ii) it exploits a {scalar} synchronizing signal; iii) it can be applied to a {wide} class of discretetime chaotic (hyperchaotic) systems; iv) it includes, as a particular case, most of the synchronization types defined so far. An example is reported, which shows in detail that exact synchronization is effectively achieved in finite time, using a scalar synchronizing signal only, for any arbitrary scaling matrix.
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60505
Bursting oscillation in CO oxidation with small excitation and the enveloping slowfast analysis method
李向红, 毕勤胜
Based on the traditional scheme for a nonlinear system with multiple time scales, the enveloping slowfast analysis method is developed in the paper, which can be employed to investigate the dynamics of nonlinear fields with multiple time scales with periodic excitation. Upon using the method, the behaviors of the kinetic model of CO oxidation on the platinum group metals have been explored in detail. Two typical bursting phenomena such as Fold/Fold/Hopf bursting and Fold/Fold bursting, are presented, the bifurcation mechanisms of which have been obtained. Furthermore, the dynamic difference between the two cases corresponding to relatively large and small perturbation frequencies, respectively, has been presented, which can be used to describe the influence of the frequencies involving in the evolution on the bursting behaviors in the system.
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60506
Nonsingular terminal sliding mode approach applied to synchronize chaotic systems with unknown parameters and nonlinear inputs
Mohammad Pourmahmood Aghababa, Hassan Feizi
This paper deals with the design of a novel nonsingular terminal sliding mode controller for finitetime synchronization of two different chaotic systems with fully unknown parameters and nonlinear inputs. We propose a novel nonsingular terminal sliding surface and prove its finitetime convergence to zero. We assume that both the master's and the slave's system parameters are unknown in advance. Proper adaptation laws are derived to tackle the unknown parameters. An adaptive sliding mode control law is designed to ensure the existence of the sliding mode in finite time. We prove that both reaching and sliding mode phases are stable in finite time. An estimation of convergence time is given. Two illustrative examples show the effectiveness and usefulness of the proposed technique. It is worthwhile noticing that the introduced nonsingular terminal sliding mode can be applied to a wide variety of nonlinear control problems.
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60507
Adaptive
H
_{∞}
synchronization of chaotic systems via linear and nonlinear feedback control
付士慧, 陆启韶, 杜莹
Adaptive
H
_{∞}
synchronization of chaotic systems via linear and nonlinear feedback control is investigated. The chaotic systems are redesigned by using the generalized Hamiltonian systems and observer approach. Based on Lyapunov's stability theory, linear and nonlinear feedback control of adaptive
H
_{∞}
synchronization is established in order to not only guarantee stable synchronization of both master and slave systems but also reduce the effect of external disturbance on an
H
_{∞}
norm constraint. Adaptive
H
_{∞}
synchronization of chaotic systems via three kinds of control is investigated with applications to Lorenz and Chen systems. Numerical simulations are also given to identify the effectiveness of the theoretical analysis.
2012 Vol. 21 (1): 60507060507 [
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60508
Predictions of pressureinduced structural transition, mechanical and thermodynamic properties of αand βSi
_{3}
N
_{4}
ceramics:
ab initio
and quasiharmonic Debye modeling
余本海, 陈东
The planewave pseudopotential method within the framework of
ab initio
technique is used to investigate the structural and elastic properties of α and βSi
_{3}
N
_{4}
. The groundstate parameters accord quite well with the experimental data. Our calculation reveals that αSi
_{3}
N
_{4}
can retain its stability to at least 40 GPa when compressed at 300 K. The α → βphase transformation would not occur in a pressure range of 0–40 GPa and a temperature range of 0–300 K. Actually, the α → βtransition occurs at 1600 K and 7.98 GPa. For α and βSi
_{3}
N
_{4}
, the
c
axes are slightly more incompressible than the a axes. We conclude that βSi
_{3}
N
_{4}
is a hard material and ductile in nature. On the other hand, αSi
_{3}
N
_{4}
is also found to be an ionic material and can retain its mechanical stability in a pressure range of 0–10 GPa. Besides, the thermodynamic properties such as entropy, heat capacity, and Debye temperature of α and βSi
_{3}
N
_{4}
are determined at various temperatures and pressures. Significant features in these properties are observed at high temperature. The calculated results are in good agreement with available experimental data and previous theoretical values. Many fundamental solidstate properties are reported at high pressure and high temperature. Therefore, our results may provide useful information for theoretical and experimental investigations of the Si
_{3}
N
_{4}
polymorphs.
2012 Vol. 21 (1): 60508060508 [
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ATOMIC AND MOLECULAR PHYSICS
63101
Onerange addition theorems for generalized integer and noninteger
μ
Coulomb, and exponential type correlated interaction potentials with hyperbolic cosine in position, momentum, and fourdimensional spaces
I. I. Guseinov
The formulae are established in position, momentum, and fourdimensional spaces for the onerange addition theorems of generalized integer and noninteger
μ
Coulomb, and exponential type correlated interaction potentials with hyperbolic cosine (GCTCP and GETCP HC). These formulae are expressed in terms of onerange addition theorems of complete orthonormal sets of
Ψ
^{α}
exponential type orbitals (
Ψ
^{α}
ETO),
φ
^{α}
momentum space orbitals (
φ
^{α}
MSO), and
z
^{α}
hyperspherical harmonics (
z
^{α}
HSH) introduced. The onerange addition theorems obtained can be useful in the electronic structure calculations of atoms and molecules when the GCTCP and GETCP HC in position, momentum, and fourdimensional spaces are employed.
2012 Vol. 21 (1): 63101063101 [
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63102
Transition probabilities and lifetimes of the lowlying levels of Fe XIV
范建中, 汪青敏, 常志伟, 董晨钟
The multiconfiguration DiracFock method is employed to calculate the transition energies, probabilities, and oscillator strengths for electric dipole allowed (E1) and forbidden (M1, E2, M2) lines for the 3s
^{2}
3p, 3s3p
^{2}
, 3s
^{2}
3d, 3p
^{3}
, and 3s3p3d configurations of Fe XIV. The lifetimes of all 40 levels of these lowlying configurations are also derived. The valencevalence and corevalence correlation effects are accounted for in a systematic way. Breit interactions and quantum electrodynamics (QED) effects are estimated in subsequent relativistic configuration interaction (CI) calculations. The present results are in good agreement with other available theoretical and experimental values, and therefore can be used for the further astrophysical investigations.
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63201
Linear ion trap imperfection and the compensation of excess micromotion
谢艺, 万威, 周飞, 陈亮, 李朝红, 冯芒
Quantum computing requires ultracold ions in a ground vibrational state, which is achieved by sideband cooling. We report our recent efforts towards the LambDicke regime which is a prerequisite of sideband cooling. We first analyse the possible imperfection in our linear ion trap setup and then demonstrate how to suppress the imperfection by compensating the excess micromotion of the ions. The ions, after the micromotion compensation, are estimated to be very close to the Dopplercooling limit.
2012 Vol. 21 (1): 63201063201 [
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63401
Nonradiative charge transfer in collisions of protons with rubidium atoms
闫玲玲, 屈一至, 刘春华, 张宇, 王建国, Buenker Robert J
The nonradiative chargetransfer cross sections for protons colliding with Rb(5s) atoms are calculated by using the quantummechanical molecularorbital closecoupling method in an energy range of 10
^{3}
keV10 keV. The total and stateselective chargetransfer cross sections are in good agreement with the experimental data in the relatively low energy region. The importance of rotational coupling for chargetransfer process is stressed. Compared with the radiative chargetransfer process, nonradiative charge transfer is a dominant mechanism at energies above 15 eV. The resonance structures of stateselective chargetransfer cross sections arising from the competition among channels are analysed in detail. The radiative and nonradiative chargetransfer rate coefficients from low to high temperature are presented.
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63402
Total cross sections for electron scattering from fluoromethanes: A revised additivity rule method
谭晓明, 赵刚
The additivity rule for electronmolecule scattering is revised by considering the difference between the free atom and the bound atom in the molecule. The total cross sections for electron scattering from fluoromethanes (CF
_{4}
, CF
_{3}
H, CF
_{2}
H
_{2}
, and CFH
_{3}
) are calculated in an energy range from 100 eV to 1500 eV by the revised additivity rule. The present calculations are compared with the original additivity rule results and the available experimental data. Better agreement with each other is obtained.
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63701
A grooved planar ion trap design for scalable quantum information processing
冀炜邦, 万金银, 成华东, 刘亮
We describe a new electrode design for a grooved surfaceelectrode ion trap, which is fabricated in printedcircuitboard technology with segmented electrodes. This design allows a laser beam to get through the central groove to avoid optical access blocking and laser scattering from the ion trap surface. The confining potentials are modeled both analytically and numerically. We optimize the radio frequency (rf) electrodes and dc electrodes to achieve the maximum trap depth for a given ion height above the trap electrodes. We also compare our design with the reality ion chip MI I for practical considerations. Comparison results show that our design is superior to MI I. This ion trap design may form the basis for large scale quantum computers or parallel quadrupole mass spectrometers.
2012 Vol. 21 (1): 63701063701 [
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ELECTROMAGNETISM, OPTICS, ACOUSTICS, HEAT TRANSFER, CLASSICAL MECHANICS, AND FLUID DYNAMICS
64101
Shrinking device realized by using layered structures of homogeneous isotropic materials
郭亚楠, 刘少斌, 赵鑫, 王身云, 陈忱
We propose the practical realization of a shrinking device by using layered structures of homogeneous isotropic materials. By mimicking the shrinking device with concentric alternating thin layers of isotropic dielectrics, the permittivity and the permeability in each isotropic layer can be properly determined from the effective medium theory in order to achieve the shrinking effect. The device realized by multilayer coating with dielectrics is validated by TE wave simulation, and good shrinking performance is demonstrated with only a few layers of homogeneous isotropic materials.
2012 Vol. 21 (1): 64101064101 [
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64201
The research of optical windows used in aircraft sensor systems
周峰, 李岩, 汤天瑾
The optical windows used in aircrafts protect their imaging sensors from environmental effects. Considering the imaging performance, flat surfaces are traditionally used in the design of optical windows. For aircrafts operating at high speeds, the optical windows should be relatively aerodynamic, but a flat optical window may introduce unacceptably high drag to the airframes. The linear scanning infrared sensors used in aircrafts with, respectively, a flat window, a spherical window and a toric window in front of the aircraft sensors are designed and compared. Simulation results show that the optical design using a toric surface has the integrated advantages of field of regard, aerodynamic drag, narcissus effect, and imaging performance, so the optical window with a toric surface is demonstrated to be suited for this application.
2012 Vol. 21 (1): 64201064201 [
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64202
Nearfield properties of diffraction through a circular subwavelengthsize aperture
王正岭, 周明, 高传玉, 张伟
Analytical nonparaxial vectorial electric field expressions for both Gaussian beams and plane waves diffracted through a circular aperture are derived by using the vector plane angular spectrum method for the first time, which is suitable for the subwavelength aperture and the nearfield region. The transverse properties of intensity distributions and their evolutions with the propagating distance, and the power transmission functions for diffracted fields containing the whole field, the evanescent field and the propagating field are investigated in detail, which is helpful for understanding the relationship between evanescent and propagating components in the nearfield region and can be applied to apertured nearfield scanning optical microscopy.
2012 Vol. 21 (1): 64202064202 [
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64203
Optical transfer function analysis of circularpupil wavefront coding systems with separable phase masks
赵廷玉, 刘钦晓, 余飞鸿
This paper proposes a simple method to achieve the optical transfer function of a circular pupil wavefront coding system with a separable phase mask in Cartesian coordinates. Based on the stationary phase method, the optical transfer function of the circular pupil system can be easily obtained from the optical transfer function of the rectangular pupil system by modifying the cutoff frequency and the onaxial modulation transfer function. Finally, a system with a cubic phase mask is used as an example to illustrate the way to achieve the optical transfer function of the circular pupil system from the rectangular pupil system.
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64204
A generalized Weyl—Wigner quantization scheme unifying
PQ
and
QP
ordering and Weyl ordering of operators
王继锁, 范洪义, 孟祥国
By extending the usual Wigner operator to the sparameterized one as (1/4π
^{2}
)∫
_{∞}
^{∞}
d
y
d
u
exp≤[i
u
≤(
qQ
) + i
y
≤(
pP
) + i(s/2)
yu
] with s being a real parameter, we propose a generalized Weyl quantization scheme which accompanies a new generalized
s
parameterized ordering rule. This rule recovers
PQ
ordering,
QP
ordering, and Weyl ordering of operators in
s
=1,1,0 respectively. Hence it differs from the CahillGlaubers' ordering rule which unifies normal ordering, antinormal ordering, and Weyl ordering. We also show that in this scheme the
s
parameter plays the role of correlation between two quadratures
Q
and
P
. The formula that can rearrange a given operator into its new
s
parameterized ordering is presented.
2012 Vol. 21 (1): 64204064204 [
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64205
Threequbit quantumgate operation with an SQUID in a cavity
石惠敏, 於亚飞, 张智明
We propose a method of realizing a threequbit quantum gate with a superconducting quantum interference device (SQUID) in a cavity. In this proposal, the gate operation involves the SQUID groundstates and the Fock states of cavity modes b and ĉ. The two fieldmodes act as the controlling qubits, and the two SQUID states form the target qubit. Since only the metastable lower levels are involved in the gate operation, the gate is not affected by the SQUID decay rates.
2012 Vol. 21 (1): 64205064205 [
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64206
Observation of linewidth narrowing due to a spontaneously generated coherence effect
田思聪, 王春亮, 康智慧, 杨秀彬, 万仁刚, 张晓军, 张航, 姜云, 崔海宁, 高锦岳
We investigate the resonance fluorescence spectrum of an atomic threelevel ladder system driven by two laser fields. We show that such a system emulates to a large degree a Vtype atom with parallel dipole momentsthe latter being a system that exhibits spontaneously generated coherence and can display ultrasharp spectral lines. We find a suitable energy scheme in a
^{85}
Rb atom and experimentally observe the narrowing of the central peak in a rubidium atomic beam. The corresponding spectrum can convincingly demonstrate the existence of spontaneously generated coherence.
2012 Vol. 21 (1): 64206064206 [
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64207
Photonnumber distribution of twomode squeezed thermal states by entangled state representation
胡利云, 王帅, 张智明
Using the entangled state representation, we convert a twomode squeezed number state to a Hermite polynomial excited squeezed vacuum state. We first analytically derive the photon number distribution of the twomode squeezed thermal states. It is found that it is a Jacobi polynomial; a remarkable result. This result can be directly applied to obtaining the photon number distribution of nonGaussian states generated by subtracting from (adding to) twomode squeezed thermal states.
2012 Vol. 21 (1): 64207064207 [
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64208
Modulation of atomic exit and injection rates on the phasedependent gain without inversion in a Doppler broadened open fourlevel system
刘中波, 贾克宁, 梁颖, 仝殿民, 樊锡君
It is shown that in a Doppler broadened open Ntype fourlevel atomic system with spontaneously generated coherence (SGC), the gain without inversion (GWI) is very sensitive to the variation of the relative phase between the probe field and the driving field; the atomic exit rate (
R
_{0}
) and the ratio (
S
) of the atomic injection rates have a considerable modulation effect on the phasedependent GWI. GWI first increases and then decreases with
R
_{0}
increasing; in a certain value range of
S
, GWI increases monotonically with
S
increasing; by adjusting the values of
R
_{0}
and
S
, in an open system a much larger GWI can be obtained than in the corresponding closed system [2011
Phys. Rev.
A
83
043805]. The modulation effects of
R
_{0}
and
S
on the phasedependent GWI in the case with the counterpropagating probe and driving fields are stronger than those in the copropagating case, GWI in the copropagating case is much larger than that in the counterpropagating case.
2012 Vol. 21 (1): 64208064208 [
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64209
Activation of silicon quantum dots and coupling between the active centre and the defect state of the photonic crystal in a nanolaser
黄伟其, 陈汉琼, 苏琴, 刘世荣, 秦朝建
A new nanolaser concept using silicon quantum dots (QDs) is proposed. The conduction band opened by the quantum confinement effect gives the pumping levels. Localized states in the gap due to some surface bonds on Si QDs can be formed for the activation of emission. An inversion of population can be generated between the localized states and the valence band in a QD fabricated by using a nanosecond pulse laser. Coupling between the active centres formed by localized states and the defect states of the twodimensional (2D) photonic crystal can be used to select the model in the nanolaser.
2012 Vol. 21 (1): 64209064209 [
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64210
Study on a Wband modified Vshaped microstrip meanderline travelingwave tube
沈飞, 魏彦玉, 许雄, 殷海荣, 宫玉彬, 王文祥
The study on a miniaturized, lowvoltage, widebandwidth, highefficiency modified Vshaped microstrip meanderline slowwave structure is presented. This structure is evolved from the original Ushaped microstrip meanderline slowwave structure, combining the advantages of a traditional microstrip and a rectangular helix. In this paper, simulations of the electromagnetic characteristics and the beamwave interaction of this structure are carried out. Our study shows that when the design voltage and the current of a sheet electron beam are set to be 4700 V and 100 mA, respectively, this miniature millimeterwave power amplifier is capable of delivering 160W output power with a corresponding gain of 37.3 dB and a maximum interaction efficiency of 34% at 97 GHz.
2012 Vol. 21 (1): 64210064210 [
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64211
Passively modelocked 2μm Tm:YAP laser with a doublewall carbon nanotube absorber
曲遵世, 王勇刚, 刘杰, 郑丽和, 苏良碧, 徐军
We report on a diodepumped passively continuous wave (cw) modelocked Tm:YAP laser with a doublewall carbon nanotube (DWCNT) absorber operating at a wavelength of 2023 nm for the first time, to the best our knowledge. The DWCNT absorber is fabricated on a hydrophilic quartz substrate by using the vertical evaporation technique. The output power is as high as 375 mW. A stable pulse train with a repetition rate of 72.26 MHz is generated with a highest single pulse energy of 5.2 μJ.
2012 Vol. 21 (1): 64211064211 [
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64212
Study on incident laser modulation using surface microdefects on KH
_{2}
PO
_{4}
crystal
陈明君, 程健, 李明全, 肖勇
KH
_{2}
PO
_{4}
crystal is a crucial optical component of inertial confinement fusion. Modulation of an incident laser by surface microdefects will induce the growth of surface damage, which largely restricts the enhancement of the laser induced damage threshold. The modulation of an incident laser by using different kinds of surface defects are simulated by employing the threedimensional finitedifference timedomain method. The results indicate that after the modulation of surface defects, the light intensity distribution inside the crystal is badly distorted, with the light intensity enhanced symmetrically. The relations between modulation properties and defect geometries (e.g., width, morphology, and depth of defects) are quite different for different defects. The modulation action is most obvious when the width of surface defects reaches 1.064 μ. For defects with smooth morphology, such as spherical pits, the degree of modulation is the smallest and the light intensity distribution seems relatively uniform. The degree of modulation increases rapidly with the increase of the depth of surface defects and becomes stable when the depth reaches a critical value. The critical depth is 1.064 μ for cuboid pits and radial cracks, while for ellipsoidal pits the value depends on both the width and the length of the defects.
2012 Vol. 21 (1): 64212064212 [
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64213
Application of a characterized differencefrequency laser source to carbon monoxide trace detection
Alireza Khorsandi, Zahra Shabani, Monireh Ranjbar, S. Ali Hoseinzadeh Salati
A tunable continuous wave (cw) midinfrared (MIR) laser based on differencefrequency generation (DFG) in a 1.5cm long AgGaS
_{2}
nonlinear crystal for trace gas detection is reported. Two visible and nearinfrared diode lasers were used as pump and signal sources. The MIRDFG laser was tunable in a wavelength range of 4.75 μm4.88 μm. The phasematching (PM) condition was noncritically achieved by adjusting the temperature of the crystal for fixed pairs of input pump and signal wavelengths. The required PM temperatures of the generated MIRDFG wavelengths have been calculated by using three sets of recent Sellmeier equations and the temperaturedispersion equations of AgGaS
_{2}
given by Willer U,
et al
. (Willer U, Blanke T and Schade W 2001
Appl. Opt
.
40
5439). Then the calculated PM temperatures are compared with the experimental values. The performance of the MIRDFG laser is shown by the trace detection of the P(16) carbon monoxide (
^{12}
C
^{16}
O) absorption line in a laboratoryfabricated absorption cell. The enhanced sensitivity of about 0.6 × 10
^{4}
was obtained through the long path absorption provided by consecutive reflections between coated cylindrical mirrors of a constructed cell.
2012 Vol. 21 (1): 64213064213 [
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64214
The effect of a magnetic field on a 2D problem of fibrereinforced thermoelasticity rotation under three theories
Kh. Lotfy
In the present paper, we introduce the coupled theory (CD), LordSchulman (LS) theory, and GreenLindsay (GL) theory to study the influences of a magnetic field and rotation on a twodimensional problem of fibrereinforced thermoelasticity. The material is a homogeneous isotropic elastic halfspace. The method applied here is to use normal mode analysis to solve a thermal shock problem. Some particular cases are also discussed in the context of the problem. Deformation of a body depends on the nature of the force applied as well as the type of boundary conditions. Numerical results for the temperature, displacement, and thermal stress components are given and illustrated graphically in the absence and the presence of the magnetic field and rotation.
2012 Vol. 21 (1): 64214064214 [
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64215
Measurement of the argongasinduced broadening and line shifting of the barium Rydberg level 6s24d
^{1}
D
_{2}
by twophoton resonant nondegenerate fourwave mixing
孙江, 熊志强, 孙娟, 王颖, 苏红新
We apply twophoton resonant nondegenerate fourwave mixing with a resonant intermediate state to the observation of the broadening and shifting of the barium Rydberg level 6s24d
^{1}
D
_{2}
by collision with argon. The collision broadening and shifting cross sections are measured. This technique is purely optical, and can investigate the pressure dependence of the transverse relaxation rate
Γ
_{21}
between the Rydberg state and an intermediate state, as well as the transverse relaxation rate
Γ
_{20}
between the Rydberg state and the ground state.
2012 Vol. 21 (1): 64215064215 [
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64216
Highorder harmonic generation in subonecycle regime
向阳, 钮月萍, 祁义红, 龚尚庆
We theoretically investigate the highorder harmonic generation from the hydrogen atom driven by the laser pulses with the durations less than the optical cycle. It is found that the switching term of the laser field may have an obvious influence on the cutoff, intensity or plateau structure of the highorder harmonic spectrum. Generally speaking, the switching term can shorten the cutoff of the highorder harmonic spectrum for a relatively longer pulse and extend the cutoff for a relatively shorter pulse.
2012 Vol. 21 (1): 64216064216 [
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64217
The signal synchronization transmission of a spatiotemporal chaos network constituted by a laser phaseconjugate wave
李文琳, 李淑凤, 李钢
The signal synchronization transmission of a spatiotemporal chaos network is investigated. The structure of the coupling function between connected nodes of the complex network and the value range of the linear term coefficient of the separated configuration in state equation of the node are obtained through constructing an appropriate Lyapunov function. Each node of the complex network is a laser spatiotemporal chaos model in which the phaseconjugate wave and the unilateral coupled map lattice are taken as a local function and a spatially extended system, respectively. The simulation results show the effectiveness of the signal synchronization transmission principle of the network.
2012 Vol. 21 (1): 64217064217 [
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64218
Elegant Ince—Gaussian breathers in strongly nonlocal nonlinear media
白志勇, 邓冬梅, 郭旗
A novel class of optical breathers, called elegant InceGaussian breathers, are presented in this paper. They are exact analytical solutions to Snyder and Mitchell's mode in an elliptic coordinate system, and their transverse structures are described by Incepolynomials with complex arguments and a Gaussian function. We provide convincing evidence for the correctness of the solutions and the existence of the breathers via comparing the analytical solutions with numerical simulation of the nonlocal nonlinear Schrödinger equation.
2012 Vol. 21 (1): 64218064218 [
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64219
Two localized CO
_{2}
laser treatment methods for mitigation of UV damage growth in fused silica
蒋勇, 向霞, 刘春明, 罗成思, 王海军, 袁晓东, 贺少勃, 任玮, 吕海兵, 郑万国, 祖小涛
Two methods: highpower, shorttime, singleshot irradiation (Method A) and lowpower, longtime, multishot irradiation (Method B) are investigated to mitigate the UV damage growth in fused silica by using a 10.6μm CO
_{2}
laser. To verify the mitigation effect of the two methods, the laser induced damage thresholds (LIDTs) of the mitigated sites are tested with a 355nm, 6.4ns Nd:YAG laser, and the light modulation of the mitigation sites are tested with a 351nm continuous Nd:YLF laser. The mitigated damaged sites treated with the two methods have almost the same LIDTs, which can recover to the level of pristine material. Compared with Method A, Method B produces mitigated sites with low crater depth and weak light modulation. In addition, there is no raised rim or redeposited debris formed around the crater edge for Method B. Theoretical calculation is utilized to evaluate the central temperature of the CO
_{2}
laser beam irradiated zone and the radius of the crater. It is indicated that the calculated results are consistent with the experimental results.
2012 Vol. 21 (1): 64219064219 [
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64220
A novel optical beam splitter based on photonic crystal with hybrid lattices
朱清溢, 付永启, 胡德清, 章志敏
A novel optical beam splitter constructed on the basis of photonic crystal (PC) with hybrid lattices is proposed in this paper. The band gap of squarelattice PC is so designed that the incident light is divided into several branch beams. Triangularlattice gradedindex PCs are combined for focusing each branch. Computational calculations are carried out on the basis of finitedifferent timedomain algorithm to prove the feasibility of our design. The waveguide is unnecessary in the design. Thus the device has functions of both splitting and focusing beams. Size of the divided beam at site of fullwidth at halfmaximum is of the order of
λ
/2. The designed splitter has the advantages that it has a small volume and can be integrated by conventional semiconductor manufacturing process.
2012 Vol. 21 (1): 64220064220 [
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64221
Experimental investigation of preirradiation effect on radiation sensitivity of temperature sensing fiber Bragg gratings
金靖, 林松, 宋凝芳
The effect of preirradiation on radiation sensitivity of fiber Bragg gratings (FBGs) is verified experimentally. FBGs are fabricated in photosensitive optical fibers and single mode fibers with Geconcentration in a range from 3 mol% to 23.37 mol% in the core. In experiments, the FBGs are subjected to twice
γ
radiation exposures to a Co
^{60}
source at a doserate of 0.1 Gy/s up to a total dose of 50 kGy. Preirradiation treatment can reduce the temperature sensitivity variation of FBGs by 18.12%35.91%, as well as Bragg wavelength shift (BWS) by 8%27.08 %. Our research demonstrates that preirradiation treatment is a feasible method to improve the radiation tolerance of FBGs.
2012 Vol. 21 (1): 64221064221 [
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64222
Optimization of regenerator based on semiconductor optical amplifier for degraded differential phase shift keying signal
马永欣, 席丽霞, 陈光, 张晓光
Real time phase regeneration is necessary for degraded phase modulation format optical communication systems. A regenerator based on the discrimitive gain effect of a semiconductor optical amplifier was proposed in recent years. In this paper, for this type of regenerator, its optimal working condition is found by solving the dynamic equations which describe the variance of the optical field and carrier density in the semiconductor optical amplifier by the finite difference method. The results show that the optimal improvement of signal
Q
factor can reach more than 2.2 dB.
2012 Vol. 21 (1): 64222064222 [
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64301
Point defect states of a hollow cylinder in twodimensional phononic crystal
高晓薇, 陈世波, 陈建兵, 郑勤红, 杨海
Point defect states in twodimensional phononic crystal of a hollow mercury cylinder in a water host are studied. An improved plane expansion method combined with the supercell technique is used to calculate the band gaps and the pressure distribution at the defect position. The sonic pressure of defect modes shows that the waves are localized at or near the defect. As the filing fraction increases, more defect modes appear in the band gaps.
2012 Vol. 21 (1): 64301064301 [
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64401
High temperature thermal behaviour modeling of largescale fused silica optics for laser facility
于景侠, 贺少勃, 向霞, 袁晓东, 郑万国, 吕海兵, 祖小涛
High temperature annealing is often used for the stress control of optical materials. However, weight and viscosity at high temperature may destroy the surface morphology, especially for the largescale, thin and heavy optics used for large laser facilities. It is necessary to understand the thermal behaviour and design proper support systems for largescale optics at high temperature. In this work, three support systems for fused silica optics are designed and simulated with the finite element method. After the analysis of the thermal behaviours of different support systems, some advantages and disadvantages can be revealed. The results show that the support with the optical surface vertical is optimal because both pollution and deformation of optics could be well controlled during annealing at high temperature. Annealing process of the optics irradiated by CO
_{2}
laser is also simulated. It can be concluded that high temperature annealing can effectively reduce the residual stress. However, the effects of annealing on surface morphology of the optics are complex. Annealing creep is closely related to the residual stress and strain distribution. In the region with large residual stress, the creep is too large and probably increases the deformation gradient which may affect the laser beam propagation.
2012 Vol. 21 (1): 64401064401 [
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64501
Symmetry of Lagrangians of a holonomic variable mass system
吴惠彬, 梅凤翔
The symmetry of Lagrangians of a holonomic variable mass system is studied. Firstly, the differential equations of motion of the system are established. Secondly, the definition and the criterion of the symmetry of the system are presented. Thirdly, the conditions under which there exists a conserved quantity deduced by the symmetry are obtained. The form of the conserved quantity is the same as that of the constant mass Lagrange system. Finally, an example is shown to illustrate the application of the result.
2012 Vol. 21 (1): 64501064501 [
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64601
Nonlinearity and periodic solution of a standardbeam balance oscillation system
李世松, 兰江, 韩冰, 谭红, 李正坤
We present the motion equation of the standardbeam balance oscillation system, whose beam and suspensions, compared with the compound pendulum, are connected flexibly and vertically. The nonlinearity and the periodic solution of the equation are discussed by the phaseplane analysis. We find that this kind of oscillation can be equivalent to a standardbeam compound pendulum without suspensions; however, the equivalent mass centre of the standard beam is extended. The derived periodic solution shows that the oscillation period is tightly related to the initial pivot energy and several systemic parameters: beam length, masses of the beam, and suspensions, and the beam mass centre. A numerical example is calculated.
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64701
Analysing the structure of the optical path length of a supersonic mixing layer by using wavelet methods
高穹, 易仕和, 姜宗福, 赵玉新, 谢文科
The nanoparticlebased planar laser scattering (NPLS) technique is used to measure the density distribution in the supersonic mixing layer of the convective Mach number 0.12, and the optical path difference (OPL), which is quite crucial for the study of aerooptics, is obtained by post processing. Based on the high spatiotemporal resolutions of the NPLS, the structure of the OPL is analysed using wavelet methods. The coherent structures of the OPL are extracted using three methods, including the methods of thresholding the coefficients of the orthogonal wavelet transform and the wavelet packet transform, and preserving a number of wavelet packet coefficients with the largest amplitudes determined by the entropy dimension. Their performances are compared, and the method using the wavelet packet is the best. Based on the viewpoint of multifractals, we study the OPL by the wavelet transform maxima method (WTMM), and the result indicates that its scaling behaviour is evident.
2012 Vol. 21 (1): 64701064701 [
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PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES
65101
Study on the electromagnetic propertiesof a coated radar absorbent
张栓勤
The solgel method is used to fabricate Fe crystalline powders coated with SiO
_{2}
. By controlling the molar ratio R of diluted water to tetraethoxysilane (TEOS), Fe powders coated with SiO
_{2}
with different morphological characteristics are fabricated. The influence of the core diameter on electromagnetic parameters is investigated. The effect of the amount of the coating material SiO
_{2}
on electromagnetic parameters is given. Radar wave absorbing properties of Fe coated with SiO
_{2}
and TiO
_{2}
respectively are compared.
2012 Vol. 21 (1): 65101065101 [
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65201
The effects of substrate temperature on ZnObased resistive random access memory devices
赵建伟, 刘凤娟, 黄海琴, 胡佐富, 张希清
Ag/ZnO/Zn/Pt structure resistive switching devices are prepared by radio frequency magnetron sputtering. The ZnO thin films are grown at room temperature and 400 ℃ substrate temperature, respectively. By comparing the data, we find that the latter device displayed better stability in the repetitive switching cycle test, and the resistance ratio between a high resistance state and a low resistance state is correspondingly increased. After 10
^{4}
s storage time measurement, this device exhibits a good retention property. Moreover, the operation voltages are very low: 0.3 V/0.7 V (OFF state) and 0.3 V (ON state). A highvoltage forming process in the initial state is not required, and a multistep reset process is demonstrated.
2012 Vol. 21 (1): 65201065201 [
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CONDENSED MATTER: STRUCTURAL, MECHANICAL, AND THERMAL PROPERTIES
66101
Evolution of the structural and optical properties of silver oxide films with different stoichiometries deposited by directcurrent magnetron reactive sputtering
赵孟珂, 梁艳, 郜小勇, 陈超, 陈先梅, 赵显伟
Nitrogen doping of silver oxide (Ag
_{x}
O) film is necessary for its application in transparent conductive film and diodes because intrinsic Ag
_{x}
O film is a ptype semiconductor with poor conductivity. In this work, a series of Ag
_{x}
O films is deposited on glass substrates by directcurrent magnetron reactive sputtering at different flow ratios (FRs) of nitrogen to O
_{2}
. Evolutions of the structure, the reflectivity, and the transmissivity of the film are studied by Xray diffractometry and sphectrophotometry, respectively. The specular transmissivity and the specular reflectivity of the film decreasing with FR increasing can be attributed to the evolution of the phase structure of the film. The nitrogen does not play the role of an acceptor dopant in the film deposition.
2012 Vol. 21 (1): 66101066101 [
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66102
The crystal structures and physical properties of the solid solution compound Ba
_{5}
Y
_{8x}
Mn
_{4}
O
_{211.5x}
(
x
=0, 1)
高庆庆, 李静波, 宋士佳, 骆军, 饶光辉, 梁敬魁
New oxometallides with the formula Ba
_{5}
Y
_{8x}
Mn
_{4}
O
_{211.5x}
(
x
=0, 1) are prepared through an atmospherecontrolled solidstate reaction. Two singlephase samples with Ba/Y/Mn atomic ratios 5/8/4 (Y8) and 5/7/4 (Y7) are obtained. The crystal structures and the physical properties of the compounds are investigated by Xray powder diffraction, magnetization, conductivity, and dielectricity measurements. The Ba
_{5}
Y
_{8x}
Mn
_{4}
O
_{211.5x}
compound is demonstrated to be a Ydeficient solid solution. The solid solution compound Ba
_{5}
Y
_{8x}
Mn
_{4}
O
_{211.5x}
crystallizes into tetragonal symmetry with the space group
I
4/
m
. Detailed structure analysis by Rietveld refinement of the Xray powder diffraction data reveals that the Y vacancies occur preferentially at the Y(2) site. Thermal magnetization measurements indicate the presence of antiferromagnetic interaction between Mn ions in the compounds, and temperaturedependent resistivity measurements show that insulatorsemiconductor transitions occur around 175 K and 170 K for the Y8 and Y7 samples, respectively. Strong frequency dependences of the dielectric constant are observed above ～ 175 K for the two compounds.
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66103
Density functional study of the pressure tensor for inhomogeneous Lennard—Jones fluids
孙宗利, 康艳霜, 康艳梅, 刘志成, 马恒心
Based on classical density functional theory, an expression of the pressure tensor for inhomogeneous fluids is presented. This takes into account greater correlation between particles, especially for systems that are geometrically confined or involve an interface. The density and pressure components of LennardJones fluids confined in hard and softened nanocavities are calculated. A comparison between the results of this work and IK expression suggests that the agreement depends on temperature. The interfacial tension for hard sphere fluids agrees well with the Monte Carlo result when the bulk density is not too large. The results of the solidfluid interfacial tension for LennardJones fluids demonstrate that different types of external potentials modulate the interfacial tension in different manners.
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66104
Azimuthal anchoring of a nematic liquid crystal on a grooved interface with anisotropic polar anchoring
周璇, 张志东, 叶文江, 宣丽
Zhang Y J
et al
. [Zhang Y J, Zhang Z D, Zhu L Z and Xuan L 2011
Liquid Cryst
.
38
355] investigated the effects of finite polar anchoring on the azimuthal anchoring energy at a grooved interface, in which polar anchoring was isotropic in the local tangent plane of the surface. In this paper, we investigate the effects of both isotropic and anisotropic polar anchoring on the surface anchoring energy in the frame of Fukuda
et al
.'s theory. The results show that anisotropic polar anchoring strengthens the azimuthal anchoring of grooved surfaces. In the oneelasticconstant approximation (
K
_{11}
=
K
_{22}
=
K
_{33}
=
K
), the surfacegrooveinduced azimuthal anchoring energy is entirely consistent with the result of Faetti, and it reduces to the original result of Berreman with an increase in polar anchoring. Moreover, the contribution of the surfacelike elastic term to the RapiniPapoular anchoring energy is zero.
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66105
Investigation of the inhibiting outdiffusion of erbium atoms to a silicononinsulator surface after annealing at high temperature
秦希峰, 李洪珍, 李双, 冀子武, 王绘凝, 王凤翔, 付刚
The annealing behaviour of 400 keV Er ions at a fluence of 2 × 10
^{15}
cm
^{2}
implanted into silicononinsulator (SOI) samples is investigated by Rutherford backscattering spectrometry of 2.1 MeV He
^{2+}
ions with a multiple scattering model. It is found that the damage close to the SOI surface is almost removed after being annealed in O
_{2}
and N
_{2}
atmospheres, successively, at 900 ℃, and that only a small number of the Er atoms segregated to the surface of the SOI sample, whereas a large number of Er atoms diffused to a deeper position because of the affinity of Er for oxygen. For the SOI sample coimplanted with Er and O ions, there is no evident outdiffusion of Er atoms to the SOI surface after being annealed in N
_{2}
atmosphere at 900 ℃.
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66106
Growth characteristics of amorphouslayerfree nanocrystalline silicon films fabricated by very high frequency PECVD at 250 ℃
郭艳青, 黄锐, 宋捷, 王祥, 宋超, 张奕雄
Amorphouslayerfree nanocrystalline silicon films were prepared by a very high frequency plasma enhanced chemical vapor deposition (PECVD) technique using hydrogendiluted SiH
_{4}
at 250 ℃. The dependence of the crystallinity of the film on the hydrogen dilution ratio and the film thickness was investigated. Raman spectra show that the thickness of the initial amorphous incubation layer on silicon oxide gradually decreases with increasing hydrogen dilution ratio. Highresolution transmission electron microscopy reveals that the initial amorphous incubation layer can be completely eliminated at a hydrogen dilution ratio of 98%, which is lower than that needed for the growth of amorphouslayerfree nanocrystalline silicon using an excitation frequency of 13.56 MHz. More studies on the microstructure evolution of the initial amorphous incubation layer with hydrogen dilution ratios were performed using Fouriertransform infrared spectroscopy. It is suggested that the high hydrogen dilution, as well as the higher plasma excitation frequency, plays an important role in the formation of amorphouslayerfree nanocrystalline silicon films.
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66301
The influence of cation additives on the NIR luminescence intensity of Er
^{3+}
doped borate glasses
周永亮, 张晓松, 徐建萍, 张忠朋, 张高峰, 魏凤巍, 李岚
Er
^{3+}
doped 25BaO(25x)SiO
_{2}
xAl
_{2}
O
_{3}
25B
_{2}
O
_{3}
transparent glasses are prepared with
x
=0, 12.5 and 25 by a solidstate reaction. The Errelated NIR luminescence intensity, which corresponds to the transition of
^{4}
I
_{15/2}

^{4}
I
_{13/2}
, is obviously altered with different silicon/aluminum ratios. The JuddOfelt parameters of the Er
^{3+}
ions are adopted to explain the intensity change in the NIR fluorescence, and the Raman scattering intensity versus the amount of Al and/or Si components are discussed. The spectra of the three samples are quite similar in the peak positions, but different in intensity. The maximal phonon density of state for the samples is calculated from the Raman spectra and is correlated to the NIR luminescence efficiency.
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66501
The effect of intragranular microstress in Al
_{2}
O
_{3}
—SiC nanocomposites
王志远, 吴裕功, 佟帅, 吴斯骐
A theoretical model is established to investigate the intragranular particle residual stress in Al
_{2}
O
_{3}
SiC nanocomposites. Using this model, we calculate the average compressive stress on the Al
_{2}
O
_{3}
grain boundary (GB) and the average tensile stress within Al
_{2}
O
_{3}
grains caused by SiC nanoparticles. The normal compressive stress strengthens the GB, and the average tensile stress weakens the grains. The model gives a reasonable interpretation of the strength changes of Al
_{2}
O
_{3}
SiC nanocomposites with the number of SiC particles.
2012 Vol. 21 (1): 66501066501 [
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66801
The effect of interfacial energy anisotropy on planar interface instability in a succinonitrile alloy under a small temperature gradient
王理林, 王志军, 林鑫, 王猛, 黄卫东
The morphological stability of a planar interface with different crystallographic orientations is studied under a small positive temperature gradient using a transparent model alloy of succinonitrile. Novel experimental apparatus is constructed to provide a temperature gradient of about 0.37 K/mm. Under this small temperature gradient, the planar interface instability depends largely on the crystallographic orientation. It is shown experimentally that the effect of interfacial energy anisotropy on planar interface stability cannot be neglected even in a small temperature gradient system. Higher interfacial energy anisotropy leads the planar interface to become more unstable, which is different from the stabilizing effect of the interfacial energy on the planar interface. The experimental results are in agreement with previous theoretical calculations and phase field simulations.
2012 Vol. 21 (1): 66801066801 [
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66802
The properties of transparent conducting molybdenumdoped ZnO films grown by radio frequency magnetron sputtering
修显武, 赵文静
Transparent conducting molybdenumdoped zinc oxide films are prepared by radio frequency (RF) magnetron sputtering at ambient temperature. The MoO
_{3}
content in the target varies from 0 to 5 wt%, and each film is polycrystalline with a hexagonal structure and a preferred orientation along the c axis. The resistivity first decreases and then increases with the increase in MoO
_{3}
content. The lowest resistivity achieved is 9.2 × 10
^{4}
Ω·cm, with a high Hall mobility of 30 cm
^{2}
·V
^{1}
·s
^{1}
and a carrier concentration of 2.3 × 10
^{20}
cm
^{3}
at an MoO
_{3}
content of 2 wt%. The average transmittance in the visible range is reduced from 91% to 80% with the increase in the MoO
_{3}
content in the target.
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66803
Molecular dynamics study of temperaturedependent ripples in monolayer and bilayer graphene on 6H—SiC surfaces
唐超, 魏晓林, 谭歆, 彭向阳, 孙立忠, 钟建新
Using classical molecular dynamics and a simulated annealing technique, we show that microscopic corrugations occur in monolayer and bilayer graphene on 6HSiC substrates. From an analysis of the atomic configurations, two types of microscopic corrugations are identified, namely periodic ripples at room temperature and random ripples at high temperature. Two different kinds of ripple morphologies, each with a periodic structure, occur in the monolayer graphene due to the existence of a coincidence lattice between graphene and the SiC terminated surface (Si or Cterminated surface). The effect of temperature on microscopic ripple morphology is shown through analysing the roughness of the graphene. A temperaturedependent multiple bonding conjugation is also shown by the broad distribution of the carboncarbon bond length and the bond angle in the rippled graphene on the SiC surface. These results provide atomiclevel information about the rippled graphene layers on the two polar faces of the 6HSiC substrate, which is useful not only for a better understanding of the stability and structural properties of graphene, but also for the study of the electronic properties of graphenebased devices.
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CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES
67101
Theoretical investigation on the electronic structure, elastic properties, and intrinsic hardness of Si
_{2}
N
_{2}
O
丁迎春, 陈敏, 高秀英, 蒋孟衡
According to the density functional theory we systematically study the electronic structure, the mechanical properties and the intrinsic hardness of Si
_{2}
N
_{2}
O polymorphs using the firstprinciples method. The elastic constants of four Si
_{2}
N
_{2}
O structures are obtained using the stressstrain method. The mechanical moduli (bulk modulus, Young's modulus, and shear modulus) are evaluated using the VoigtReussHill approach. It is found that the tetragonal Si
_{2}
N
_{2}
O exhibits a larger mechanical modulus than the other phases. Some empirical methods are used to calculate the Vickers hardnesses of the Si
_{2}
N
_{2}
O structures. We further estimate the Vickers hardnesses of the four Si
_{2}
N
_{2}
O crystal structures, suggesting all Si
_{2}
N
_{2}
O phases are not the superhard compounds. The results imply that the tetragonal Si
_{2}
N
_{2}
O is the hardest phase. The hardness of tetragonal Si
_{2}
N
_{2}
O is 31.52 GPa which is close to values of βSi
_{3}
N
_{4}
and γSi
_{3}
N
_{4}
.
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67102
Effects of Ndoping concentration on the electronic structure and optical properties of Ndoped βGa
_{2}
O
_{3}
张丽英, 闫金良, 张易军, 李厅
The electronic structures and the optical properties of Ndoped βGa
_{2}
O
_{3}
with different Ndoping concentrations are studied using the firstprinciples method. We find that the N substituting O(1) atom is the most stable structure for the smallest formation energy. After Ndoping, the charge density distribution significantly changes, and the acceptor impurity level is introduced above the valence band and intersects with the Fermi level. The impurity absorption edges appear to shift toward longer wavelengths with an increase in Ndoping concentration. The complex refractive index shows metallic characteristics in the Ndoped βGa
_{2}
O
_{3}
.
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67103
Comparative study of adsorption characteristics of Cs on the GaN (0001) and GaN (0001) surfaces
杜玉杰, 常本康, 王洪刚, 张俊举, 王美山
The adsorption characteristics of Cs on GaN (0001) and GaN (000
1
) surfaces with a coverage from 1/4 to 1 monolayer have been investigated using the density functional theory with a planewave ultrasoft pseudopotential method based on firstprinciples calculations. The results show that the most stable position of the Cs adatom on the GaN (0001) surface is at the Nbridge site for 1/4 monolayer coverage. As the coverage of Cs atoms at the Nbridge site is increased, the adsorption energy reduces. As the Cs atoms achieve saturation, the adsorption is no longer stable when the coverage is 3/4 monolayer. The work function achieves its minimum value when the Cs adatom coverage is 2/4 monolayer, and then rises with Cs atomic coverage. The most stable position of Cs adatoms on the GaN (000
1
) surface is at H3 site for 1/4 monolayer coverage. As the Cs atomic coverage at H3 site is increased, the adsorption energy reduces, and the adsorption is still stable when the Cs adatom coverage is 1 monolayer. The work function reduces persistently, and does not rise with the increase of Cs coverage.
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67201
Influence of a twodimensional electron gas on current—voltage characteristics of Al
_{0.3}
{Ga}
_{0.7}
N/GaN high electron mobility transistors
冀东, 刘冰, 吕燕伍, 邹杪, 范博龄
The
JV
characteristics of Al
_{t}
Ga
_{1t}
N/GaN high electron mobility transistors (HEMTs) are investigated and simulated using the selfconsistent solution of the Schrödinger and Poisson equations for a twodimensional electron gas (2DEG) in a triangular potential well with the Al mole fraction
t
=0.3 as an example. Using a simple analytical model, the electronic drift velocity in a 2DEG channel is obtained. It is found that the current density through the 2DEG channel is on the order of 10
^{13}
A/m
^{2}
within a very narrow region (about 5 nm). For a current density of 7 × 10
^{13}
A/m
^{2}
passing through the 2DEG channel with a 2DEG density of above 1.2 × 10
^{17}
m
^{2}
under a drain voltage
V
_{ds}
=1.5 V at room temperature, the barrier thickness
L
_{b}
should be more than 10 nm and the gate bias must be higher than 2 V.
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67202
Improved performance of organic lightemitting diodes with dual electron transporting layers
焦志强, 吴晓明, 华玉林, 穆雪, 毕文涛, 白娟娟, 印寿根
In this study the performance of organic lightemitting diodes (OLEDs) are enhanced significantly, which is based on dual electron transporting layers (Bphen/CuPc). By adjusting the thicknesses of Bphen and CuPc, the maximal luminescence, the maximal current efficiency, and the maximal power efficiency of the device reach 17570 cd/m
^{2}
at 11 V, and 5.39 cd/A and 3.39 lm/W at 3.37 mA/cm
^{2}
respectively, which are enhanced approximately by 33.4%, 39.3%, and 68.9%, respectively, compared with those of the device using Bphen only for an electron transporting layer. These results may provide some valuable references for improving the electron injection and the transportation of OLED.
2012 Vol. 21 (1): 67202067202 [
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67301
A comparative investigation of an AB and AAstacked bilayer graphene sheet under an applied electric field: A density functional theory study
汪涛, 郭清, 刘艳, 盛况
An AB and AAstacked bilayer graphene sheet (BLG) under an electric field is investigated by
ab initio
calculation. The interlayer distance between the two layers, band structures, and atomic charges of the system are investigated in the presence of different electric fields normal to the BLG. The ABstacked BLG is able to tune the bandgap into 0.234 eV with the increase of the external electronic field to 1 V/nm, however, the AAstacked BLG is not sensitive to the external electric field. In both the cases, the spacing between the BLG slightly change in terms of the electric field. The charges in the ABstacked BLG are increased with the increase of the electric field, which is considered to be the reason that causes the bandgap opening in the ABstacked BLG.
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67302
A density functional theory study on the adsorption of CO and O
_{2}
on Cuterminated Cu
_{2}
O (111) surface
李敏, 张俊英, 张跃, 王天民
The adsorptions of CO and O
_{2}
molecules individually on the stoichiometric Cuterminated Cu
_{2}
O (111) surface are investigated by firstprinciples calculations on the basis of the density functional theory. The calculated results indicate that the CO molecule preferably coordinates to the Cu
_{2}
site through its C atom with an adsorption energy of 1.69 eV, whereas the O
_{2}
molecule is most stably adsorbed in a tilt type with one O atom coordinating to the Cu
_{2}
site and the other O atom coordinating to the Cu
_{1}
site, and has an adsorption energy of 1.97 eV. From the analysis of density of states, it is observed that Cu 3d transfers electrons to 2π orbital of the CO molecule and the highest occupied 5σ orbital of the CO molecule transfers electrons to the substrate. The sharp band of Cu 4s is delocalized when compared to that before the CO molecule adsorption, and overlaps substantially with bands of the adsorbed CO molecule. There is a broadening of the 2π orbital of the O
_{2}
molecule because of its overlapping with the Cu 3d orbital, indicating that strong 3d2π interactions are involved in the chemisorption of the O
_{2}
molecule on the surface.
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67303
A GaAs planar Schottky varactor diode for lefthanded nonlinear transmission line applications
董军荣, 杨浩, 田超, 黄杰, 张海英
The lefthanded nonlinear transmission line (LHNLTL) based on monolithic microwave integrated circuit (MMIC) technology possesses significant advantages such as wide frequency band, high operating frequency, high conversion efficiency, and applications in millimeter and submillimeter wave frequency multiplier. The planar Schottky varactor diode (PSVD) is a major limitation to the performance of the LHNLTL frequency multiplier as a nonlinear component. The design and the fabrication of the diode for such an application are presented. An accurate largesignal model of the diode is proposed. A 16 GHz39.6 GHz LHNLTL frequency doubler using our largesignal model is reported for the first time. The measured maximum output powers of the 2nd harmonic are up to 8 dBm at 26.4 GHz, and above 0 dBm from 16 GHz to 39.6 GHz when the input power is 20 dBm. The application of the LHNLTL frequency doubler furthermore validates the accuracy of the largesignal model of the PSVD.
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67304
Farinfrared electroluminescence characteristics of an Sibased photodiode under a forward DC bias current
肖文波, 何兴道, 张志敏, 高益庆, 刘江涛
At room temperature, the bias dependence of a farinfrared electroluminescence image of a photodiode is investigated in the dark condition. The results show that the electroluminescence image can be used to detect defects in the photodiode. Additionally, it is found that the electroluminescence intensity has a power law dependence on the dc bias current. The photodiode ideality factor could be obtained by a fitting a relationship between the electroluminescence intensity and the bias current. The device defect levels will be easily determined according to the infrared image and the extracted ideality factor value. This work is of guiding significance for current solar cell testing and research.
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67305
Performance of La
_{2}
O
_{3}
/InAlN/GaN metal—oxide—semiconductor high electron mobility transistors
冯倩, 李倩, 邢韬, 王强, 张进成, 郝跃
We report on the performance of La
_{2}
O
_{3}
/InAlN/GaN metaloxidesemiconductor high electron mobility transistors (MOSHEMTs) and InAlN/GaN high electron mobility transistors (HEMTs). The MOSHEMT presents a maximum drain current of 961 mA/mm at
V
_{gs}
=4 V and a maximum transconductance of 130 mS/mm compared with 710 mA/mm at
V
_{gs}
=1 V and 131 mS/mm for the HEMT device, while the gate leakage current in the reverse direction could be reduced by four orders of magnitude. Compared with the HEMT device of a similar geometry, MOSHEMT presents a large gate voltage swing and negligible current collapse.
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67306
Modulation of electrical and optical properties of galliumdoped ZnO films by radio frequency magnetron sputtering
梁爽, 梅增霞, 杜小龙
Gadoped ZnO (GZO) films are prepared on amorphous glass substrates at room temperature by radio frequency magnetron sputtering. The results reveal that the gallium doping efficiency, which will have an important influence on the electrical and optical properties of the film, can be governed greatly by the deposition pressure and film thickness. The position shifts of the ZnO (002) peaks in Xray diffraction (XRD) measurements and the varied Hall mobility and carrier concentration confirms this result. The low Hall mobility is attributed to the grain boundary barrier scattering. The estimated height of barrier decreases with the increase of carrier concentration, and the trapping state density is nearly constant. According to defect formation energies and relevant chemical reactions, the photoluminescence (PL) peaks at 2.46 eV and 3.07 eV are attributed to oxygen vacancies and zinc vacancies, respectively. The substitution of more Ga atoms for Zn vacancies with the increase in film thickness is also confirmed by the PL spectrum. The obvious blueshift of the optical bandgap with an increase of carrier concentration is explained well by the BursteinMoss (BM) effect. The bandgap difference between 3.18 eV and 3.37 eV, about 0.2 eV, is attributed to the metalsemiconductor transition.
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67501
The mixedspins 1/2 and 3/2 Blume—Capel model with a random crystal field
Erhan Albayrak
The random crystal field (RCF) effects are investigated on the phase diagrams of the mixedspins 1/2 and 3/2 BlumeCapel (BC) model on the Bethe lattice. The bimodal random crystal field is assumed and the recursion relations are employed for the solution of the model. The system gives only the secondorder phase transitions for all values of the crystal fields in the nonrandom bimodal distribution for given probability. The randomness does not change the order of the phase transitions for higher crystal field values, i.e., it is always secondorder, but it may introduce firstorder phase transitions at lower negative crystal field values for the probability in the range about 0.20 and 0.45, which is only the secondorder for the nonrandom case in this range. Thus our work claims that randomness may be used to induce firstorder phase transitions at lower negative crystal field values at lower probabilities.
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67502
Texture and selfbiased property of an oriented Mtype barium ferrite thick film by tape casting
陈大明, 刘颖力, 李元勋, 杨楷, 张怀武
In this paper, the oriented Mtype barium ferrite (BaM) thick films with different thicknesses are prepared by tape casting. It is found that the crystallographic alignment degree (
f
), the pore and the squareness ratio (M
_{r}
/M
_{s}
) are not affected by the thickness of the film. XRD and SEM results show that the thick film has hexagonal morphology with a crystal texture of
c
axis grains perpendicular to film plane. The hysteresis curve indicates that the BaM thick film exhibits a selfbiased property with a remanent magnetization of 3.30 T, a squareness ratio (
M
_{r}
/
M
_{s}
) of 0.81, and a coercivity of 0.40 T. The results show that the BaM thick film has potential for use in selfbiasing microwave devices, and also proves that the tape casting technique is capable of fabricating highquality barium ferrite films, thus providing a unique opportunity to realize the large area production of thick film.
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67503
Defects mediated ferromagnetism in a Vdoped 6H—SiC single crystal
卓世异, 刘学超, 熊泽, 闫文盛, 忻隽, 杨建华, 施尔畏
Undoped and Vdoped 6HSiC single crystals have been grown by the physical vapor transport method. The V concentration is determined to be 3.76 × 10
^{17}
at/cm
^{3}
and 6.14 × 10
^{17}
at/cm
^{3}
by secondary ion mass spectrometry for low Vdoped and high Vdoped SiC samples, respectively. The undoped 6HSiC shows diamagnetism, while the Vdoped 6HSiC exhibits weak ferromagnetism. The lower Vdoped sample shows stronger ferromagnetism compared to that of the higher Vdoped sample. However, the structural characterization indicates that the lower Vdoped SiC has a relative poor crystalline quality. It is found that both V dopants and defects are essential for introducing ferromagnetic exchange in Vdoped SiC single crystals.
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67701
Optimized growth and dielectric properties of barium titanate thin films on polycrystalline Ni foils
梁伟正, 吉彦达, 南天翔, 黄江, 曾慧中, 杜辉, 陈充林, 林媛
Barium titanate (BTO) thin films were deposited on polycrystalline Ni foils by using the polymer assisted deposition (PAD) technique. The growth conditions including ambient and annealing temperatures were carefully optimized based on thermal dynamic analysis to control the oxidation processing and interdiffusion. Crystal structures, surface morphologies, and dielectric performance were examined and compared for BTO thin films annealed under different temperatures. Correlations between the fabrication conditions, microstructures, and dielectric properties were discussed. BTO thin films fabricated under the optimized conditions show good crystalline structure and promising dielectric properties with
ε
_{r}
～ 400 and tan
δ
<0.025 at 100 kHz. The data demonstrate that BTO films grown on polycrystalline Ni substrates by PAD are promising in device applications.
2012 Vol. 21 (1): 67701067701 [
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