共查询到20条相似文献,搜索用时 15 毫秒
1.
Ruchi Singh M.K. Maurya T.K. Yadav D.P. Singh R.A. Yadav 《Optics & Laser Technology》2011,43(1):95-101
Intensity dependent space charge field and gain coefficient in the photorefractive medium due to the two interfering beams have been calculated by solving the material rate equations in presence of externally applied dc electric field. The gain coefficient has been studied with respect to variations in the input intensity, modulation depth, concentration ratio and normalized diffusion field in the absence and presence of the externally applied dc electric field. Space charge field has also been computed by varying the intensity ratio in the presence and absence of the externally applied dc electric field. It has been found that the rate of change of the space charge field with the normalized dc field decreases with the increasing intensity ratio for different values of the normalized diffusion field. It has also been found that the externally applied dc electric field has appreciable effect only when it is larger than the diffusion field. 相似文献
2.
The effect of dc electric field E on the characteristics, propagation conditions, and temperature delay coefficients of Lamb and SH waves in a piezoelectric langasite plate is considered based on the theory of acoustic-wave propagation in piezoelectric crystals exposed to such a field. The cuts characterized by a thermal stability and large electromechanical coupling coefficient are determined. 相似文献
3.
Modulational instability of a far infrared laser has been studied in a piezoelectric semiconductor in the presence of a dc electric field. The growth rate and the threshold value of the electric field required for the onset of instability have been calculated. 相似文献
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Chiral Symmetry Breaking During Growing Process of NaClO3 Crystal under Direct-Current Electric Field
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We investigate the influence of dc electric field on chiral symmetry breaking during the growing process of NaClO3 crystal. Nucleation and growth of NaClO3 are completed from an aqueous solution by a fast cooling temperature technology. A pair of polarization microscopes are used to identify a distribution of chiral crystals. Experimental results indicate that the dc electric field has an effect on distribution of chirality, but the direction of the dc electric field is not sensitive to the chiral autocatalysis and selectivity, i.e. the nature convection driving by the gravity does not play an important role on a thin layer of NaClO3 solution. The experimental phenomena may be elucidated by the ECSN mechanism. 相似文献
7.
X.L. Lei S.Y. Liu 《The European Physical Journal B - Condensed Matter and Complex Systems》2000,13(2):271-277
We investigate the magnetotransport in semiconductors under the influence of a dc or slowly-varying electric field, an intense
polarized radiation field of terahertz frequency, and a uniform magnetic field, being in arbitrary directions and having arbitrary
strengths. Effective force- and energy-balance equations are derived by using a gauge that the magnetic field and the high-frequency
radiation field are described by a vector potential and the dc or slowly-varying field by a scalar potential, and by distinguishing
the slowly-varying velocity from the rapidly-oscillating velocity related to the high-frequency field. These equations, which
include the elastic photon process and all orders of multiphoton absorption and emission processes, are applied to the examination
of the effect of a terahertz radiation on the magnetophonon resonance of the longitudinal resistivity in the transverse configuration
in nonpolar and polar semiconductors. We find that the previous zero-photon resonance peaks are suppressed by the irradiation
of the terahertz field, while many new peaks, which may be related to multiphoton absorption and emission processes, emerge
and can become quite distinct, at moderately strong radiation field.
Received 17 May 1999 相似文献
8.
It has been revealed that, as an external dc electric field is applied to graphene with the Hubbard interaction between electrons,
a spontaneous electric field perpendicular to the applied field can appear. This effect can be due to the nonequilibrium electron
subsystem in graphene. The spontaneous field characteristics have been found as a function of the parameters of the problem. 相似文献
9.
Measurements of engineered subwavelength microstructures can be designed to have positive or negative and μ at desired frequencies. We present transmission measurements of a metamaterial consisting of split ring resonators (SRR). Results for different polarizations and propagation directions are presented. The transmission shows a dip even for propagations perpendicular to the SRR plane, provided that the incident electric field is parallel to the sides of the split ring resonators (SRRs) which contain the cuts. The experimental results agree well with the theoretical calculations. 相似文献
10.
K. R. Izrael’yants A. P. Orlov A. L. Musatov E. V. Blagov 《Physics of the Solid State》2016,58(5):1020-1023
Frequency characteristics of field electron emission from long carbon nanofilaments/nanotubes in strong dc and weak ac electric fields have been investigated. A series of narrow peaks with a quality factor of up to 1100 has been discovered in the frequency range of hundreds of kilohertz. The analysis has shown that these peaks are probably associated with mechanical oscillations of the carbon nanofilaments/nanotubes driven by the ac electric field. 相似文献
11.
The characteristics of the magnetoelectric interaction in a planar nickel-lead-zirconate-titanate structure have been studied
in a dc electric field applied to the ferroelectric layer. A hysteretic field dependence of the efficiency and frequency of
the resonant magnetoelectric interaction has been revealed, and the vanishing of the interaction efficiency in the range of
polarization switching fields due to changes in the permittivity, the piezoelectric modulus, and the dielectric loss of the
ferroelectric has been observed. It has been shown that the electric field leads to a significant change in the rigidity of
the ferroelectric layer. 相似文献
12.
The processes of polarization evolution in single crystals of the PbMg1/3Nb2/3O3 model ferroelectric relaxor in a sinusoidal electric field are investigated at temperatures near and above the temperature T d 0 of destruction of the induced ferroelectric state upon heating in zero electric field. The polarization switching current loops are measured in the ac electric field applied along the 〈111〉 and 〈110〉 pseudocubic directions. The electroluminescence intensity loops are obtained under the combined action of ac and dc electric fields applied along the 〈100〉 direction. In a certain temperature range above T d 0 and the freezing temperature T f in lead magnesium niobate, there are electric current anomalies, that correspond to the dynamic formation and subsequent destruction of the ferroelectric macroregions throughout each half-cycle of the ac electric field. The measurements of electroluminescence hysteresis loops demonstrate that the observed depolarization delay (related to the ac electric field amplitude) increases with an increase in the dc electric field and decreases as the ac field amplitude increases. The nature of the observed phenomena is discussed. 相似文献
13.
The effect of transverse entrainment of charge carriers by two electromagnetic waves propagating in mutually perpendicular directions in a semiconductor with a parabolic dispersion law has been investigated. The dc component of the electric current density that appears in the direction perpendicular to the wave vectors has been calculated in the constant relaxation time approximation. It has been shown that the transverse dc current vanishes at a particular phase difference of the incident waves determined by the relaxation time of charge carriers in the material. 相似文献
14.
Franz R. Aussenegg Max E. Lippitsch Humbert M. Noll Erich J. Schieffer 《Physics letters. A》1978,68(2):194-196
The vibrational Raman bands of some simple liquids are investigated on the influence of an external electric dc field. Thereby the electric field strength is varied in the range of 0.1 to 1 MV/cm. The experiments demonstrate that Raman intensities and depolarization ratios increase with increasing field strength and — after passing a maximum — decrease with even higher field strengths. In mixtures the field dependence of Raman intensity takes a different course than in pure liquids. 相似文献
15.
The density of the current associated with the drag of charge carriers in a superlattice by an elliptically polarized electromagnetic wave is calculated. Two cases of the mutual orientation of the Umov-Poynting vector and the superlattice axis, i.e., their parallel and perpendicular orientations, are analyzed. It is shown that, for the parallel orientation, the radioelectric effect can change sign. The influence of the longitudinal dc electric field on the radioelectric effect is investigated under the conditions where a circularly polarized electromagnetic wave propagates along the superlattice axis. The current density is studied as a function of the electric field strength and the electromagnetic wave intensity. It is demonstrated that the direction of the electric current is changed at specific values of the dc field strength and the wave intensity. 相似文献
16.
Electric field distribution is an important parameter for nanostructure arrays in nanobiosensing appfications. It can influence the sensitivity and the resolution of nanobiosensors. We focus on the effect of media on the electric field distribution of a rhombic silver nanostructure array. The finite-difference time-domain algorithm- based numerical calculation method is used to monitor the electric field distribution of the silver nanostructures when the refractive index of the medium around the nanostructure array is changed. The calculated results show that tuning the refractive index of the medium around silver can have a considerable influence on the electric field distribution in the reflection and transmission directions. This effect can be used to increase the extinction efficiency and to improve the resolution of the spectra for nanobiosensing. 相似文献
17.
采用电滞回线方法和偏置直流电场中叠加小交变电场方法研究了锆钛酸铅反铁电陶瓷材料在强电场作用下的介电行为.测量结果显示,锆钛酸铅反铁电材料的介电常数随外加电场强度呈非线性变化,在反铁电 铁电转变的电场区间形成介电峰.表征极化强度随电场强度变化率的微分介电常数εd峰值出现在反铁电 铁电转换电场强度处,最高达到41000.随着偏置电场增加反铁电向铁电体转变过程中,小信号介电常数εc减小;在电场降低铁电回复成反铁电过程中,小信号介电常数εc增大,小信号介电常数εc峰先于微分介电常数εd峰出现.根据电场作用下反铁电
关键词:
锆钛酸铅反铁电陶瓷
介电行为
强电场条件 相似文献
18.
The temperature dependence of the dielectric nonlinearities in a PMN single crystal and in 9/65/35 PLZT ceramics has been determined by measuring the first and third harmonic response as well as the dielectric behavior as a function of the dc electric field. In zero field a paraelectric-to-glass, and, in a high enough dc field, a glass-to-ferroelectriclike crossover in the temperature dependence of the nonlinear response have been observed. Both crossovers agree with the predictions of the spherical random-bond-random-field model. Relaxors thus undergo in zero field a transition to a spherical glass, while above the critical field a transition into a ferroelectric state occurs. 相似文献
19.
Effect of electric field on the percolation phase transition in lead scandotantalate single crystals
The effect of a dc electric field on the phase transition process in lead scandotantalate single crystals differing in the degree of ion ordering has been studied by small-angle light scattering (SAS). The spontaneous phase transition occurring in these crystals is shown to be accompanied by a sharp SAS intensity peak indicating the percolation nature of this transition. A phase diagram in the field-temperature coordinates has been constructed for all the PST crystals studied in the work. The electric field and the temperature variation rate have been found to affect the SAS intensity. 相似文献
20.
V. V. Gladkii V. A. Kirikov S. V. Nekhlyudov T. R. Volk L. I. Ivleva 《Physics of the Solid State》2000,42(7):1334-1340
The anomalies of polarization (mismatch of hysteresis loops for several first repolarization cycles, the absence of specific coercive field, etc.) in quasi-static and dc electric fields have been found in the strontium barium niobate relaxor ferroelectric. The anomalies are associated with a highly inhomogeneous structure of the crystal, which is considered a clearly defined nonergodic system with a random distribution of strong local internal fields. The energy distributions of potential barriers for the polarization and the depolarization are obtained at different electric field strengths and temperatures. 相似文献