共查询到20条相似文献,搜索用时 15 毫秒
1.
A.V. ButenkoV. Sandomirsky R. KahatabiZ. Dashevsky V. KasiyanZ. Zalevsky Y. Schlesinger 《Physica B: Condensed Matter》2012,407(3):439-450
We describe here the first comprehensive investigation of a pyroelectric response of a p-n junction in a non-polar paraelectric semiconductor. The pyroelectric effect is generated by the, temperature dependent, built-in electrical dipole moment. High quality PbTe p-n junctions have been prepared specifically for this experiment. The pyroelectric effect was excited by a continuous CO2 laser beam, modulated by a mechanical chopper. The shape and amplitude of the periodic and single-pulse pyroelectric signals were studied as a function of temperature (10-130 K), reverse bias voltage (up to −500 mV) and chopping frequency (4-2000 Hz). The pyroelectric coefficient is ≈10−3 μC/cm2K in the temperature region 40-80 K. The developed theoretical model quantitatively describes all the experimental features of the observed pyroelectric effect. The time evolution of the temperature within the p-n junction was reconstructed. 相似文献
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Magnetoelectric and pyroelectric properties have been investigated in heterostructures of nickel zinc ferrite (NZFO)-lead zirconate titanate (PZT) and lanthanum calcium manganite (LCMO)-PZT. The magnetoelectric (ME) coupling, mediated by mechanical strain, is found to be two orders of magnitude stronger in NZFO-PZT than in LCMO-PZT. The pyroelectric effect is investigated by measuring the current through the sample as the temperature is varied at 0.1 K/s. For NZFO-PZT the pyroelectric coefficient is in the range 0.2-15 nC/cm2 K, depending on the temperature. A much weaker current is observed in LCMO-PZT. A reversal in the current direction is detected when the thermal cycle is switched from heating to cooling. The pyroelectric coefficient is found to scale with the strength of ME interactions. A clear correlation between pyroelectric current and ME interactions is evident from the results. 相似文献
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The current state of the set of problems associated with the study and application of the pyroelectric effect at low (T<30 K) temperatures is outlined. The reasons for the qualitatively different temperature dependences of the total pyroelectric coefficient γσ(T) in linear pyroelectrics and ferroelectrics are discussed. An analysis is given of the reasons why the theoretical temperature dependences obtained for the primary pyroelectric coefficient γε(T) adequately describe the experimental γσ(T) dependences for all materials studied. In this connection, the correctness of determining the secondary pyroelectric coefficient γS(T) from the macroscopically measured coefficients of thermal expansion is considered. The potential of thermodynamically nonequilibrium polar media and low-temperature pyroelectric materials is substantiated. The review consists of the following sections: (1) an introduction; (2) the theory of low-temperature pyroelectricity; (3) experimental procedures; (4) discussion of the experimental data: (A) perfect single crystals, (B) the problem of the secondary pyroelectric coefficient, (C) imperfect single crystals; (5) pyroelectric materials for low-temperature applications; and (6) a conclusion. 相似文献
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P. Szklarz 《Journal of Physics and Chemistry of Solids》2005,66(1):121-125
The pyroelectric effect is measured in tricycloheylmethanolmethanol (TCHM) crystal around the second-order phase transition at 104 K. The presented results confirm that the spontaneous polarization exists in the low temperature phase of TCHM and is reversible in external electric field. It is suggested that TCHM is an improper ferroelectric below 104 K. 相似文献
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The pyroelectric properties of samples cut from various growth sectors of RbTiOPO4 single crystals grown from solution in a melt were measured in the temperature range from 4.2 to 300 K. The experimental values of the pyroelectric coefficient range from ?1.3 × 10?5 to ?4.6 × 10?5 C/m2 K. For the samples cut from the (100) sector, pronounced anomalies were revealed at 85 and 275 K, which, in our opinion, can be due to the contribution of associates formed by the coordination tetrahedra PO4(1) and PO4(2) and interstitial rubidium Rb i . At T > 280 K, superionic conductivity begins to manifest itself in all of the samples studied, which indicates the decomposition of the dipole complexes with increasing temperature. From the measured pyroelectric coefficient and birefringence along the polar direction, the spontaneous polarization of rubidium titanyl is calculated to be 0.5 C/m2 at 250 K, which is comparable in magnitude to that of lithium tantalate. 相似文献
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采用C-V法,根据C-2-V曲线和C-3-V曲线,并结合C-V幂律指数k,分析了T=25~-195℃温度范围内,温度变化对GaN基蓝光发光二极管pn结类型的影响。实验结果表明:当T为25℃和-50℃时,C-2-V呈明显的线性关系,同时幂律指数k为0.5,说明该温度范围内的pn结类型为严格的突变结;而温度降低至-100℃时,k值变为0.45,说明pn结类型开始发生变化;当温度继续降低至-150℃和-195℃时,幂律指数k分别为0.30和0.28,说明pn结类型已经发生了变化,变为非突变非缓变结。造成这一现象的原因是低温导致的载流子冻析效应,以及晶体的缺陷和界面态形成的局域空间电荷区在低温环境下,影响了pn结原来的空间电荷分布,并改变了pn结类型。 相似文献
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Results are presented of experimental studies of how the spontaneous polarization of β-BaB2O4 (BBO) varies with temperature in the range from 2.5 to 90 K. Values of the pyroelectric coefficient γ
s are calculated, and effective values of the Debye temperature (Θ=112 K) and the Einstein temperature (ΘE=28 K) are estimated. It is shown that the dominant contribution to γ
s comes from acoustic lattice modes. A mechanism is proposed to explain why the temperature dependence of the pyroelectric
effect in linear pyroelectric materials is different from that in ferroelectrics.
Fiz. Tverd. Tela (St. Petersburg) 39, 1631–1633 (September 1997) 相似文献
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Yingbang Yao Bernd Ploss C. L. Mak K. H. Wong 《Applied Physics A: Materials Science & Processing》2010,99(1):211-216
BiFeO3 (BFO) ceramics were prepared by a modified solid-state-reaction method which adopts a higher heating/cooling rate during
the sintering process than usually used. It was found that the calcination temperature T
cal (from 400 to 750°C) does not influence the BFO phase formation, while the sintering temperature T
sin (from 815 to 845°C) dominates the phase purity. The optimum sintering temperature was in the range from 825 to 835°C. The
optimized samples exhibit saturated ferroelectric hysteresis loops with a remnant polarization of 13.2 μC/cm2. The measured piezoelectric coefficient d
33 was 45 pC/N. No remnant magnetization was observed in all of the samples. The pyroelectric properties were studied as a function
of temperature and frequency. A pyroelectric coefficient as high as 90 μC/m2 K was obtained at room temperature in the optimized sample. An abrupt decrease of the pyroelectric coefficient was observed
at temperatures between 70 and 80°C. On the basis of our results, BFO may have the potential for pyroelectric applications. 相似文献
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Cong Chen Tingyin Ning Heng Lu Can Wang Dongxiang Zhang Pei Wang Hai Ming Yueliang Zhou Guozhen Yang 《Applied Physics A: Materials Science & Processing》2010,99(4):849-852
A pyroelectric behavior was observed in CaCu3Ti4O12 films and the pyroelectric coefficient was measured to be 1.35×10?7 C/cm2?K for a film with thickness of 700 nm from 295 K to 340 K, larger than those of most pyroelectric materials. It was observed that the pyroelectric coefficient increased with the thickness of films from 300 to 700 nm. The origin of pyroelectric effect is proposed to depend on the distortion of the Ti–O octahedron due to the presence of Ti3+ ions. Comparing with the measurement result of an unpolarized film, our study strongly supports the interpretation of relaxor ferroelectric behavior in CaCu3Ti4O12. 相似文献
11.
《Solid State Communications》1989,70(12):1095-1098
Pyroelectric methods are used for estimation of the polarization of the CDP crystal. The peak value of the pyroelectric coefficient is observed at 154.5 K. The phase of CDP above Tc up to ca. 230 K is revealed to be a polar one with polarization fluctuations in this temperature region. 相似文献
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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
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M. Marinelli F. Mercuri U. Zammit R. Pizzoferrato 《Applied Physics A: Materials Science & Processing》1991,52(2):115-118
Thermal diffusivity of various compounds used as coupling fluids in photopyroelectric experiments have been measured at room temperature and at 80 K. Measurements on high vacuum silicone grease have also been performed as a function of temperature and an increase in the thermal diffusivity values with decreasing temperature has been found. Two phase transitions in the LiTaO3 pyroelectric transducer have been observed at 200 and 225 K. 相似文献
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Young Joon Ko Yong Keun ParkByung Kil Yun Minbaek LeeJong Hoon Jung 《Current Applied Physics》2014,14(11):1486-1491
We report the pyroelectric power generation of a relaxor ferroelectric 0.7Pb(Mg1/3Nb2/3)O3–0.3PbTiO3 (PMN–PT) single crystal. For a temperature variation rate of 0.5 K/s, the PMN–PT generated a closed-circuit current of 10 nA and an open-circuit voltage of 1.1 V at room temperature. The pyroelectric current and voltage of the PMN–PT single crystal were proportional to the temperature variation rate and were sharply enhanced near the structural phase-transition temperature. Additionally, the PMN–PT pyroelectric generator produced stable power for excessive thermal cycling and was highly sensitive to random thermal fluctuations. Our results indicate the potential importance of PMN–PT for high-power pyroelectric generator applications. 相似文献
18.
Bongsoo Lee Wook Jae Yoo Dong Hyun Cho Kyoung Won Jang Soon-Cheol Chung Gye-Rae Tack 《Optical Review》2007,14(5):355-357
In this study, we measured an infrared radiation which is transferred by a silver halide optical fiber from a heat source
using a radiometer system for low-temperature measurements. To increase the amount of infrared radiation through the silver
halide optical fiber and to the pyroelectric sensor, infrared optical devices used were an infrared focusing lens and a collimator.
The relationship between the temperatures of a heat source and the measured radiometer signals were determined. The measurable
temperature range of a fiber-optic temperature sensor using a pyroelectric sensor was from 298 to 333 K. It is expected that
a noncontact low-temperature sensor using an infrared optical fiber can be developed for medical and industrial usages based
on the results of this study. 相似文献
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对六种钨青铜结构的铌酸盐铁电晶体进行了从15K到室温范围的介电特性及热电特性的研究。分析其介电特性和热电特性与极化电场的关系,用X射线粉末衍射进行佐证。证实在50—70K的范围内,SBN,PBN,KNSBN三类铁电钨青铜型铌酸盐晶体均存在着一个新的相变。相变是由点群4mm铁电相到点群mm2铁电相的转变。铁电自发极化方向由四方晶胞的e轴方向转变到正交晶胞的b轴方向。介电特性的高频及低频测量表明该相变具有扩散(或称瀰散)型特征。比热的实验结果证明相变是属于高于一阶相变的高阶相变。对相变前
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对六种钨青铜结构的铌酸盐铁电晶体进行了从15 K 到室温范围的介电特性及热电特性的研究. 分析其介电特性和热电特性与极化电场的关系, 用x 射线粉末衍射进行佐证. 证实在50 一70 K 的范围内, SBN , PBN , KNSBN 三类铁电钨青铜铌酸盐晶体均存在着一个新的相变. 相变是由点群4mm铁电相到点群mm2 铁电相的转变. 铁电自发极化方向由四方晶胞的c轴方向转变到正交晶胞的b 轴方向.介电特性的高频及低频测量表明该相变具有扩散(或称弥散)型特征. 比热的实验结果证明相变是属于高于一阶相变的高阶相变. 对相变前后的晶胞结构提出了一个模型解释.
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