共查询到20条相似文献,搜索用时 31 毫秒
1.
《Infrared Physics & Technology》1999,40(2):71-78
The contribution of the tertiary pyroelectric effect in LiTaO3 type II pyroelectric detectors is discussed according to the theory of thermoelastics and piezoelectrics, and the spatial bound charge and responsivity generated by the contribution of tertiary pyroelectric effect are described. 相似文献
2.
Low temperature measurements of the charge released (or absorbed) by prepolarized crystalline samples of ferroelectric potasium dihydrogen phosphate clearly indicate that just above 3 K the samples absorb charge, (i.e. the spontaneous polarization increases slightly). After passing through a maximum, the samples begin to release charge at 15.3 K, implying a change of sign in the pyroelectric coefficient, a behavior which had been only observed previously in a few non-ferroelectric or polycrystalline pyroelectric materials. 相似文献
3.
A. Peláiz-Barranco A. C. García-Wong Y. González-Abreu Y. Gagou P. Saint-Grégoire 《Applied Physics A: Materials Science & Processing》2013,112(2):419-423
The thermally stimulated processes in a samarium-modified lead titanate ferroelectric system are analyzed from the thermally stimulated depolarization discharge current. The discharge due to the space charge injected during the poling process, the pyroelectric response and a conduction process related to oxygen vacancies are evaluated considering a theoretical decomposition by using a numerical method. The pyroelectric response is separated from other components to evaluate the polarization behavior and some pyroelectric parameters. High remanent polarization, pyroelectric coefficient and merit figure values are obtained at room temperature. 相似文献
4.
M. K. Kerimov M. A. Kurbanov F. G. Agaev S. N. Musaeva É. A. Kerimov 《Physics of the Solid State》2005,47(4):710-714
The effect of the electric discharge-enhanced thermal crystallization of the polymer phase on the structure and pyroelectric properties of a polymer-pyroelectric composite is considered. It is shown that the changes in the polymer-phase structure during the electric discharge-enhanced thermal crystallization cause the number of charge carriers localized at the interface due to electrothermal polarization and the pyroelectric coefficient of the polymer-ceramics composite to increase noticeably. 相似文献
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在300—20K的温度范围内观测了用丘克拉斯基法生长的Li0.025Na0.975NbO3晶体的介电、铁电和热电特性。介电常数,极化强度和热电性的反常表示该晶体在低温时发生相变。此相变有特别大的热滞(约80K),降温时发生于180K附近,升温时发生于260K附近。测量了晶体的室温结构,指出了可能的低温相点群。观测了热电电荷的时间响应,报道了热电电荷随时间改变符号的特异现象,认为其起因是相变过程中两相共存。
关键词: 相似文献
7.
Infrared holographic recording in a two-step process is demonstrated in stoichiometric iron-doped lithium tantalate crystals. Through absorption of two intersecting infrared pulses (A = 1064 nm) a temperature grating and thus a modulated pyroelectric field build up. Free electrons, excited by homogeneous light of a shorter wavelength (lambda = 532 nm) drift in this field, and a phase hologram is stored that can be read nondestructively. The change in refractive index depends mainly on the absorption coefficient at the wavelength of the recording light and on the intensity of the infrared light. The proposed method may be extended to telecommunication wavelengths by choice of suitable dopants. 相似文献
8.
Grating spacing dependence of nonvolatile holographic recording in doubly doped lithium niobate crystals is theoretically investigated allowing arbitrary charge transport lengths. It is shown that the nonvolatile refractive index modulation initially increases with increasing grating spacing, then a saturation behavior arises because of the dominant bulk photovoltaic effect. Although different charge transport length results in different nonvolatile refractive index modulation, the grating spacing dependence of nonvolatile holographic recording obeys almost the same rules for arbitrary charge transport lengths. The experimental results obtained by recording nonvolatile holograms in LiNbO3:Cu:Ce crystals with different grating spacing are consistent with the theoretical analyses. 相似文献
9.
Tryglicine sulphate (TGS) is one of the most extensively studied ferroelectric materials, which undergoes second order phase transition and shows the pyroelectric effect. In our present experiments we study the electric properties of TGS, in relation to domain switching, observing the samples’ response to controlled temperature pulses. The charge released in the processes of domain switching was previously studied under constant temperature growth. Our method allows us to observe the released pyroelectric charge in both the ferroelectric and paraelectric phases. To perform our experiment we designed new measurement software and constructed a novel thermostatic sample holder containing Peltier’s cells as heating/cooling elements. 相似文献
10.
T. Nakaoka S. Kako Y. Arakawa 《Physica E: Low-dimensional Systems and Nanostructures》2006,32(1-2):148
We have experimentally and theoretically investigated quantum confined Stark effect in hexagonal self-assembled GaN/AlN quantum dots. We have observed a blueshift of up to 100 meV for vertical electric field applied against the built-in electric field while we have observed a redshift for the electric field along the built-in field. The experimental result is compared with a charge self-consistent effective mass calculation, taking into account strain, piezoelectric charge, and pyroelectric charge. The tunability of the emission energy and the exciton binding energy is discussed. 相似文献
11.
W. Künstler M. Wegener M. Seiß R. Gerhard-Multhaupt 《Applied Physics A: Materials Science & Processing》2001,73(5):641-645
Films of poly(vinylidene fluoride-hexafluoropropylene) copolymer [P(VDF-HFP)] were cast from a dimethylsulfoxide (DMSO)/acetone
solution of Solef?85-15 P(VDF-HFP) copolymer powder grade 21508. Undrawn and uniaxially drawn cast copolymer films were investigated
with respect to their piezo- and pyroelectric properties. Quasistatic charge integration was employed for the determination
of the poling-field dependence of the piezoelectric d31 and pyroelectric p3 coefficients. In addition, the thermal stability of the pyroelectric effect was studied with a combination of thermally stimulated
discharge (TSD) and temperature-modulation techniques. Cast copolymer films could withstand electrical poling fields of up
to 400 MV/m. The maximum values of d31=30 pC/N and p3=49 μC/(m2K) for uniaxially drawn samples are similar to those found on commercial PVDF films and much higher than those on pure PVDF
films cast from solution. Samples kept for 5 min at 150 °C still exhibit 30–40% of the initial pyroelectric effect [up to
around 20 μC/(m2K)]. After this annealing step, no further decay of the pyroelectric coefficient could be observed during storage at 120 °C
for several hours.
Received: 5 July 2001 / Accepted: 27 July 2001 / Published online: 2 October 2001 相似文献
12.
In this paper we use the AdS/CFT correspondence to study dark soliton solutions in a holographic model of a relativistic superfluid.
We calculate the length scales corresponding to the condensate and the charge density depletion, and find relation with the
chemical potential. We compare our solutions with the quasiparticle excitations above the holographic superfluid and find
that the scale of the excitations is comparable to the soliton coherence length scales. 相似文献
13.
The recent introduction of high quality charge coupled device(CCD) detectors,in conjunction with holographic filter technology,has revolutionised the size and diversity of Raman spectrometers. 相似文献
14.
A. Miemiec 《Fortschritte der Physik》2004,52(4):360-366
We discuss the holographic c‐function and describe an algorithm for the practical computation of the changing central charge in arbitrary RG‐flows. The conclusions are drawn from studying a particular example, which is worked out in detail. The renormalisation procedure of hep‐th/0112150 necessary to obtain the central charge is reviewed. 相似文献
15.
Diganta Parai Debabrata Ghorai Sunandan Gangopadhyay 《General Relativity and Gravitation》2018,50(11):149
In this paper, we analytically investigate the noncommutative effects of a charged black hole on holographic superconductors in the probe limit. The effects of charge of the black hole is investigated in our study. Employing the Sturm–Liouville eigenvalue method, the relation between the critical temperature and charge density is analytically investigated. The condensation operator is then computed. It is observed that condensate gets harder to form for large values of charge of the black hole. 相似文献
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Trapped charge‐induced pyroelectric‐like transient response in single high‐resistivity Sb2Se3 nanowires
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Dynamic scanning photocurrent microscopy was applied to Sb2Se3 crystalline single nanowires (NWs) to analyze their transient photocurrent responses. These NWs exhibited switching behavior with rapid rise and decay times upon illumination by laser pulses. The estimated spectral responsivity and external quantum efficiency for a freshly‐prepared NW at a bias voltage of 0.3 V and excitation wavelength of 488 nm were ~16.9 mA/W and ~42.9%, respectively. A pyroelectric‐like current transient was observed with reduced spectral responsivity when nonpolar Sb2Se3 single‐crystalline NWs were excited by laser pulses. Because Sb2Se3 NWs were nonpyroelectric or ferroelectric, the pyroelectric‐like current could possibly be attributed to temperature dependent nonlinear space‐charge distributions. Defects produced by the external electrical bias generated and re‐distributed space charges in the NWs. As a result, the temperature dependent inhomogeneous electric field led to nonlinear expansions or contractions of the lattice (electrostriction) that can produce pyroelectric current. We obtained a lower bound of equivalent pyroelectric coefficient α ≥ 60.09 μC/m2 K from these materials by fitting the electrical transients. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
18.
Holographic data storage is promised to be the next-generation optical storage technology for many years. The Zn:Fe:LiNbO3 crystal is studied widely because of its promising holographic storage properties. The forced oscillator model is used to explain the self-erasing phenomenon in the reduced Zn:Fe:LiNbO3 crystals. It is showed that the total spatial charge field is dominated by two kinds of carrier with different respond time, which are electron and hole, respectively. The cooperative action of two kinds carrier induces that the total charge field non-monotonically varies with the recording time. The same diffraction efficiency of hologram with equal exposure energy is realized by the self-erasing property. The precision of the optical correlation recognition based on holographic storage will be improved. 相似文献
19.
利用全息技术在偶氮聚合物薄膜中记录了拓扑荷数q=–1,1,2,4的涡旋光场,并将记录的原始叉形光栅与计算全息光栅进行对比,对不同拓扑荷数涡旋光的记录速率和偶氮材料的可重复擦写性能进行了测试;记录完成后,将复现涡旋光与高斯光束干涉,并与原始涡旋光和原始叉形光栅对比,分析了记录质量.实验结果表明:高阶涡旋光场的全息叉形光栅会在记录过程中发生劈裂,轻微劈裂的涡旋光束仍维持一个稳定的环状结构;全息记录过程中不同拓扑荷数的涡旋光束记录速率较为统一,偶氮材料可经过上百次的擦写而不出现疲劳;再现涡旋光与原始涡旋光在光强分布结构上保持高度一致,再现涡旋光的干涉条纹与原始涡旋全息光栅保持高度一致,涡旋光及其携带的拓扑荷信息可被有效记录和读取. 相似文献
20.
A theoretical investigation is made of the field structure in a holographic grating formed by TE0 modes in a planar photorefractive waveguide by the photogalvanic recording mechanism. Waveguides with three characteristic refractive index profiles are considered, namely, a step function, a parabola, and a hyperbolic secant squared. A comparison is made between the light field distributions of TE0 modes in waveguides having the different profiles. The field structure of the space charge in planar holographic gratings is analyzed for their initial formation phase. It is shown that the space charge field has a similar structure for all three waveguide types considered when planar photorefractive gratings are recorded by TE0 modes.Institute of Automated Control Systems and Radio Electronics, Tomsk. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 11, pp. 85–92, November, 1993. 相似文献