Study on Thermal Hysteresis of Elastic Modulus in Granular Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O

1990 ◽  
Vol 195 ◽  
Author(s):  
Yening Wang ◽  
Linhai Sun ◽  
Jin Wu ◽  
Min Gu
Keyword(s):  
Elastic Modulus ◽  
Single Crystal ◽  
Pore Size ◽  
Wide Temperature Range ◽  
Thermal Hysteresis ◽  
Coarse Grained ◽  
First Order ◽  
Temperature Range

ABSTRACTA large thermal hysteresis ( > 100 K) of elastic modulus was measured for coarse grained Y-Ba-Cu-O and Bi-Sr-Ca-Cu-O. Whereas, only a small thermal hysteresis (2∼3 K) near the velocity minima at 240 K, and 150 K was observed in Bi2 Sr2 CaCu2 O8 single crystal, which were found to be associated with phaselike transitions (PLT). The investigations of isothermal recovery of modulus for coarse grained YBCO and BSCCO disclose that the large thermal hysteresis may be attributed to the defects of pore size generated in the interconnecting region between grains as a result of PLT of weak first order but covering a wide temperature range. The mechanism of a large thermal hysteresis for coarse grained samples has been discussed in detail.

Elastic Constants in C-plane of Single Crystal Bi 2Sr 2Ca Cu 208 between 80 K and 260 K

1990 ◽  
Vol 193 ◽  
Author(s):  
Jin Wu ◽  
Yening Wang ◽  
Yifeng Yan ◽  
Zhongxian Zhao
Keyword(s):  
Shear Modulus ◽  
Single Crystal ◽  
Temperature Dependence ◽  
Elastic Constants ◽  
Wide Temperature Range ◽  
Sound Propagation ◽  
Anisotropic Elasticity ◽  
Ultrasonic Velocities ◽  
Temperature Range

ABSTRACTThe temperature dependence of the in-plane C11 C22. C12 and C66 modes between 80 and 260 K of superconducting crystals of Bi2Sr2Ca1Cu208 have been obtained via the measurements of ultrasonic-velocities. The anisotropic elasticity in the a-b plane of single crystal Bi2 Sr2Ca1Cu2O8 is manifest. The shear modulus of sound propagation along the [110] with the polarization has been also calculated and shows an overall trend of softening over a wide temperature range above Tc. The shear modulus C6 6 shows three obvious softening minima around 240–250 K, 150 K and 100 K.

Hypersonic and Dielectric Studies of Relaxor Ferroelectric Single Crystal

1999 ◽  
Vol 604 ◽  
Author(s):  
Chi-Shun Tu ◽  
V.H. Schmiidt ◽  
C.-H. Yeh ◽  
L.-F. Chen ◽  
C.-L. Tsai
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Single Crystal ◽  
Thermal Hysteresis ◽  
Relaxor Ferroelectric ◽  
Dipolar Relaxation ◽  
First Order ◽  
Dielectric Data ◽  
Scattering Spectra ◽  
Ferroelectric Single Crystal

AbstractBoth the longitudinal (LA) Brillouin back-scattering spectra and dielectric permittivity along the [001] direction have been measured as a function of temperature for a relaxor ferroelectric single crystal (PbMg1/3Nb2/3O3)0.68(PbTiO3)0.32 (PMN-32%PT). A sharp ferroelectric phase transition (which is associated with a Landau-Khalatnikov-like phonon damping maximum) was observed near 445 K. As temperature increases, a diffuse phase transition was detected near 280 K. In addition, the nature of the thermal hysteresis for the dielectric permittivity confirms that these transitions (near 280 and 445 K for heating procedure) are diffuse first-order and first-order, It respectively. The dielectric data prove the existence of an electric dipolar relaxation process below 300 K.

Ultrasonic Relaxation in Phase Transition Region in Ferroelectric Semiconductors of Sn2P2S6 Family

2012 ◽  
Vol 184 ◽  
pp. 345-350
Author(s):  
Vytautas Samulionis ◽  
Juras Banys ◽  
Yulian Vysochanskii
Keyword(s):  
Phase Transition ◽  
Ultrasonic Velocity ◽  
Thermal Hysteresis ◽  
Ultrasonic Attenuation ◽  
Landau Theory ◽  
Velocity Change ◽  
First Order ◽  
Temperature Range ◽  
Large Hysteresis ◽  
Relative Change

The paper presents recent results of ultrasonic investigation of Sn2P2S6 family ferroelectric crystals and their solid solutions in the temperature range 100-300 K. It was shown that in Sn2P2(S,Se)6 crystals the critical ultrasonic velocity slowing down for longitudinal waves propagating along main crystallographic directions is quite sharp and large. The relative change of longitudinal ultrasonic velocity along z-axis at the phase transition gradually increased from 10 % in pure Sn2P2S6 till 25 % for sample with 0.4 content of Se. Such large velocity change causes the large ultrasonic attenuation anomaly. The increase of relaxation time: τ=τ0/(TC-T) leads to the increase of attenuation. Prefactor τ0 was shown to be very small and the critical attenuation anomaly arises in the narrow temperature range close to phase transition. In the 0.4 Se sample the phase transition is of the first order because small thermal hysteresis exists. The ultrasonic velocity behaviour in the ferroelectric phase was described using Landau theory and free energy expansion including sixth order terms. For (Sn,Pb)2P2S6 system the critical ultrasonic anomalies were smaller and the phase transition temperature substantially decreased (for 0.45 Pb sample the phase transition point was at Tc =140 K). The ultrasonic anomalies at phase transition in (PbxSn1-x)2P2S6 have large hysteresis showing that transition is of the first order, far from the critical point.

A thermal [1,3] sigmatropic rearrangement: thermolysis of 2,2-bis(ethylthio)-3,3-dimethyl-4-pentenal

1981 ◽  
Vol 59 (21) ◽  
pp. 3120-3122 ◽  
Author(s):  
Gordon S. Bates ◽  
S. Ramaswamy
Keyword(s):  
Solvent Effect ◽  
Wide Temperature Range ◽  
Sigmatropic Rearrangement ◽  
Positive Entropy ◽  
First Order ◽  
Temperature Range ◽  
First Order Kinetics ◽  
Sigmatropic Shift ◽  
Entropy Of Activation

2,2-Bis(ethylthio)-3,3-dimethyl-4-pentenal was found to quantitatively isomerize to 2,2-bis(ethylthio)-5-methyl-4-hexenal over a wide temperature range (130–170 °C). This rearrangement can formally be regarded as a [1,3] sigmatropic shift. The reaction, which could be conveniently monitored by 1Hmr spectroscopy, was found to obey first order kinetics. The substantial positive entropy of activation (+ 61.5 J deg−1 mol−1) for the reaction and the negligible solvent effect (decane vs. DMF) are both consistent with a proposed diradical pathway.

Features of the photoconductivity of the quasi-one-dimensional compound TiS3

2021 ◽  
Author(s):  
S.A. Nikonov ◽  
I.G. Gorlova ◽  
S.G. Zybtsev ◽  
V.Ya. Pokrovskii
Keyword(s):  
Phase Transitions ◽  
Single Crystal ◽  
Wide Temperature Range ◽  
Direct Evidence ◽  
Nonlinear Conductivity ◽  
One Dimensional ◽  
Temperature Range ◽  
Near Ir ◽  
Linear And Nonlinear ◽  
Magnetic Conductivity

Problem formulating. The features of linear and nonlinear conductivity, magnetic conductivity, thermopower, and the Hall effect observed on TiS3 whiskers indicate phase transitions to a state of CDW in this compound, but there is no direct evidence yet. The study of photoconductivity would allow us to learn more about the nature of these phase transitions. Goal. Study of the effect of radiation in the range from near-IR to near-UV on the conductivity of single-crystal TiS3 whiskers at 4.2 <T<300 K and search for features of photoconductivity in the temperature range of the suggested phase transitions. Result. Features of the photoconductivity of TiS3 at temperatures of 50 K and 15 K, at which the −dlnσ/d(1/T) maxima were previously observed, are found. A decrease in photoconductivity at these temperatures indicates a change in the electronic spectrum, which may be associated with the formation of CDW. Practical meaning. In the case of developing TiS3-based photosensors, it is important to study the photoconductivity in a wide temperature range.

Novel KDP-ADP Nanocomposites

2013 ◽  
Vol 200 ◽  
pp. 144-148 ◽  
Author(s):  
A. Ciżman ◽  
Ewa Rysiakiewicz-Pasek ◽  
J. Kutrowska ◽  
R. Poprawski
Keyword(s):  
Phase Transition ◽  
Dielectric Permittivity ◽  
Size Effect ◽  
Pore Size ◽  
Wide Temperature Range ◽  
Dielectric Anomaly ◽  
Average Pore ◽  
Porous Glasses ◽  
Temperature Range ◽  
Pore Sizes

The influence of the size effect on the features of ADP-KDP-porous glasses composites was studied. The dielectric permittivity results of mixed ADP and KDP embedded into porous glasses with different average pore sizes in a wide temperature range are presented. The data obtained indicate that pore size affects the nature of the dielectric anomaly in the vicinity of phase transition regions.

scholarly journals Thermal stimulated current response in cupric oxide single crystal thin films over a wide temperature range

2016 ◽  
Vol 50 (3) ◽  
pp. 035303
Author(s):  
Kungan Yang ◽  
Shuxiang Wu ◽  
Fengmei Yu ◽  
Wenqi Zhou ◽  
Yunjia Wang ◽  
...  
Keyword(s):  
Thin Films ◽  
Single Crystal ◽  
Wide Temperature Range ◽  
Cupric Oxide ◽  
Current Response ◽  
Temperature Range

SAFT-γ force field for the simulation of molecular fluids: 4. A single-site coarse-grained model of water applicable over a wide temperature range

2015 ◽  
Vol 113 (9-10) ◽  
pp. 1228-1249 ◽  
Author(s):  
Olga Lobanova ◽  
Carlos Avendaño ◽  
Thomas Lafitte ◽  
Erich A. Müller ◽  
George Jackson
Keyword(s):  
Force Field ◽  
Wide Temperature Range ◽  
Single Site ◽  
Coarse Grained ◽  
Molecular Fluids ◽  
Temperature Range ◽  
Coarse Grained Model

Electro-caloric effect in a BCZT single crystal

CrystEngComm ◽  
2018 ◽  
Vol 20 (11) ◽  
pp. 1597-1602 ◽  
Author(s):  
Donglin Liu ◽  
Qiang Li ◽  
Qingfeng Yan
Keyword(s):  
Curie Temperature ◽  
Single Crystal ◽  
Wide Temperature Range ◽  
Temperature Range ◽  
Caloric Effect

The electro-caloric effect of the [001]-oriented (Ba,Ca)(Zr,Ti)O3 (BCZT) single crystal was investigated in a wide temperature range from −100 °C to Curie temperature (122 °C).

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