scholarly journals Enhanced Electrocaloric Effect in 0.73Pb(Mg1/3Nb2/3)O3-0.27PbTiO3 Single Crystals via Direct Measurement

Crystals ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 451 ◽  
Author(s):  
Biao Lu ◽  
Xiaodong Jian ◽  
Xiongwei Lin ◽  
Yingbang Yao ◽  
Tao Tao ◽  
...  
Keyword(s):  
Single Crystals ◽  
Room Temperature ◽  
Indirect Method ◽  
Phenomenological Theory ◽  
Measured Temperature ◽  
Electrocaloric Effect ◽  
Temperature Changes ◽  
Temperature Range ◽  
Maxwell Relation ◽  
Adiabatic Temperature Change

Electrocaloric properties of [110] and [111] oriented 0.73Pb(Mg1/3Nb2/3)O3-0.27PbTiO3 single crystals were studied in the temperature range of 293–423 K. The Maxwell relations and the Landau–Ginsburg–Devonshire (LGD) phenomenological theory were employed as the indirect method to calculate the electrocaloric properties, while a high-resolution calorimeter was used to measure the adiabatic temperature change of the electrocaloric effect (ECE) directly. The results indicate that the directly measured temperature changes of ΔT > 2.5 K at room temperature were procured when the applied electric field was reversed from 1 MV/m to −1 MV/m, which are larger than those deduced pursuant to the Maxwell relation, and even larger than those calculated using the LGD theory in the temperature range of 293–~380 K.

scholarly journals PSEUDO-GAP FEATURES OF INTRINSIC TUNNELING IN (HgBr2)-Bi2212 SINGLE CRYSTALS

1999 ◽  
Vol 13 (29n31) ◽  
pp. 3758-3763 ◽  
Author(s):  
AUGUST YURGENS ◽  
DAG WINKLER ◽  
TORD CLAESON ◽  
SEONG-JU HWANG ◽  
JIN-HO CHOY
Keyword(s):  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
Unit Cell ◽  
Superconducting Gap ◽  
Axis Direction ◽  
Temperature Range ◽  
Dynamic Conductance

The c-axis tunneling properties of both pristine Bi2212 and its HgBr 2 intercalate have been measured in the temperature range 4.2-250 K. Lithographically patterned 7-10 unit-cell heigh mesa structures on the surfaces of these single crystals were investigated. Clear SIS-like tunneling curves for current applied in the c-axis direction have been observed. The dynamic conductance d I/ d V(V) shows both sharp peaks corresponding to a superconducting gap edge and a dip feature beyond the gap, followed by a wide maximum, which persists up to a room temperature. Shape of the temperature dependence of the c-axis resistance does not change after the intercalation suggesting that a coupling between CuO 2-bilayers has little effect on the pseudogap.

scholarly journals Effect of LiNbO3 on the Electrocaloric Performance of 0.94BNT-0.06BT Ceramic Materials

2021 ◽  
Author(s):  
Jing Chen ◽  
lei Wu ◽  
Luanfan Duan ◽  
Dongren Liu
Keyword(s):  
Ceramic Material ◽  
Room Temperature ◽  
Ceramic Materials ◽  
Adiabatic Temperature ◽  
Cooling Effect ◽  
Material System ◽  
Temperature Changes ◽  
Cooling Temperature ◽  
Temperature Range

Abstract Considering that the electric refrigeration temperature range of 0.94BNT-0.06BT ceramic materials is 100 ~ 140℃, the electric refrigeration performance of the 0.94BNT-0.06BT ceramic material system was modified by LiNbO3 doping to reduce the cooling temperature. As a result, the refrigeration temperature range of the 0.94BNT-0.06BT ceramic material system was lowered to 25 ~ 80℃, achieving its cooling effect near room temperature, and in this temperature range, the adiabatic temperature changes ∆T > 0.6K.

Plastic Deformation of Mo(Si,Al)2 Single Crystals with the C40 Structure

1996 ◽  
Vol 460 ◽  
Author(s):  
M. Moriwaki ◽  
K. Ito ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Single Crystals ◽  
Deformation Behavior ◽  
Basal Slip ◽  
Room Temperature ◽  
Slip Systems ◽  
Temperature Range ◽  
Al Content ◽  
Partial Dislocations ◽  
Increasing Temperature ◽  
Critical Resolved Shear Stress

ABSTRACTThe deformation behavior of single crystals of Mo(Si,Al)2 with the C40 structure has been studied as a function of crystal orientation and Al content in the temperature range from room temperature to 1500°C in compression. Plastic flow is possible only above 1100°C for orientations where slip along <1120> on (0001) is operative and no other slip systems are observed over whole temperature range investigated. The critical resolved shear stress for basal slip decreases rapidly with increasing temperature and the Schmid law is valid. Basal slip appears to occur through a synchroshear mechanism, in which a-dislocations (b=1/3<1120>) dissociate into two synchro-partial dislocations with the identical Burgers vector(b*1/6<1120>) and each synchro-partial further dissociates into two partials on two adjacent planes.

Plastic Deformations in L10-Ordered Single Crystals with their c/a Ratios Less than Unity

2007 ◽  
Vol 561-565 ◽  
pp. 459-462
Author(s):  
Katsushi Tanaka ◽  
Hiromitsu Ide ◽  
Yoshinori Sumi ◽  
Kyosuke Kishida ◽  
Haruyuki Inui
Keyword(s):  
Shear Stress ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Room Temperature ◽  
The Other ◽  
Compressive Deformation ◽  
Positive Temperature ◽  
Plastic Deformations ◽  
Temperature Range ◽  
Critical Resolved Shear Stress

Compressive deformation of L10-ordered single crystals of FePd whose c/a ratio less than unity have been investigated from room temperature to 823 K. The results show that the critical resolved shear stress (CRSS) for octahedral glide of ordinary dislocations is smaller than that of super-lattice dislocations in all the temperature range investigated, that is the opposite sense to the case of Ti-56 mol% Al. The CRSS for ordinary dislocations virtually independent to the temperature. On the other hand, the CRSS for super dislocations exhibits a weak positive temperature dependence from room temperature up to 573 K and decreases in higher temperatures.

Thermoelectric Power Factor of Polycrystalline La0.75Sr0.25Co1-xMnxO3-δCeramics

2009 ◽  
Vol 1166 ◽  
Author(s):  
Julio E. Rodríguez ◽  
J. A. Niño
Keyword(s):  
Transport Properties ◽  
Thermoelectric Power ◽  
Power Factor ◽  
Figure Of Merit ◽  
Room Temperature ◽  
Manganese Content ◽  
Solid State Reaction Method ◽  
Measured Temperature ◽  
Thermoelectric Power Factor ◽  
Temperature Range

AbstractThermoelectric properties of polycrystalline La0.75Sr0.25Co1-xMnxO3-δ(0<x<0.08) (LSCoO-Mn) compounds have been studied. The samples were grown by solid-state reaction method; their transport properties were studied in the temperature range between 100 and 290K, as a function of temperature and the manganese content. The Seebeck coefficient (S) is positive over the measured temperature range and its magnitude increases with the manganese content up to values close to 160 μV/K. The electrical resistivity (ρ) goes from metallic to semiconducting behavior as the Mn level increases, at room temperature, ρ(T) exhibit values less than 4mΩ-cm. From S(T), ρ(T) and κ(T) data, the thermoelectric power factor and the figure of merit were determined. These performance parameters reach maximum values around 18 μW/K2-cm and 0.2, respectively. The observed behavior in the transport properties become these compounds potential thermoelectric materials, which could be used in thermoelectric applications.

Soft and Hard Modes of Deformation in Mosi2 Single Crystals

1994 ◽  
Vol 364 ◽  
Author(s):  
K. Ito ◽  
T. Yano ◽  
H. Inui ◽  
M. Yamaguchi
Keyword(s):  
Single Crystals ◽  
Plastic Flow ◽  
Deformation Behavior ◽  
Crystal Orientation ◽  
Room Temperature ◽  
Intermediate Temperature ◽  
Slip Systems ◽  
Anomalous Increase ◽  
Temperature Range ◽  
Intermediate Temperature Range

AbstractThe deformation behavior of MoSi2 single crystals has been studied in the temperature range of -196<1500°C. While [001]-oriented crystals can be plastically deformed only above 1300°C, plastic flow is possible from temperatures as low as room temperature for single crystals with orientations other than [001]. Five slip systems, {110)<111], {011)<100], {010)<100], {023)<100] and {013)<331], are identified to be operative, depending on crystal orientation. An anomalous increase in CRSS is observed in the intermediate temperature range for the former three slip systems. Schmid’s law is generally valid for the soft modes, {110)<111], {011)<100] and {023)<100]. In contrast, the CRSS for the hard mode, {013)<331], strongly depends on crystal orientation with the higher values for orientations closer to [001].

Temperature dependence of piezoelectric properties of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals

2003 ◽  
Vol 18 (2) ◽  
pp. 537-541 ◽  
Author(s):  
Ping-chu Wang ◽  
Xiao-ming Pan ◽  
Dong-lin Li ◽  
Yuan-wei Song ◽  
Hao-su Luo ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Temperature Dependence ◽  
Single Crystals ◽  
Phase Transition Temperature ◽  
Room Temperature ◽  
Piezoelectric Properties ◽  
Device Design ◽  
Temperature Range ◽  
Approach Zero

Piezoelectric properties k33 and d33 of 0.67 Pb(Mg1/3Nb2/3)O3–0.33 PbTiO3 single crystals grown by a modified Bridgman method were measured in the temperature range of 20–150 °C. Recoverability of the properties after the samples were heated to 110 °C, above the ferroelectric–ferroelectric (F–F) phase transition temperature of the composition, was found. From 20 to approximately 80 °C, k33 increases slightly, while d33 is almost doubled. Between approximately 90 and 100 °C, k33 decreases sharply to roughly a level of PZT-5 ceramics and d33 decreases to about 700 pC/N. They increase again with further increase of temperature; at 140 °C they attain 0.74 and approximately 1300 pC/N, respectively, and then decrease quickly and approach zero at about 150 °C. When heating to 110 °C followed by cooling to room temperature, the property decay is small. After more than one dozen heating–cooling cycles, k33 and d33 tend to be stable at 0.89 and approximately 1220 pC/N, respectively. The results might be helpful for device design and applications of PMN–PT single crystals.

High temperature dielectric relaxation anomalies in Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals

RSC Advances ◽  
2015 ◽  
Vol 5 (96) ◽  
pp. 78414-78421 ◽  
Author(s):  
G. Murugesan ◽  
R. Nithya ◽  
S. Kalainathan ◽  
Shamima Hussain
Keyword(s):  
High Temperature ◽  
Dielectric Relaxation ◽  
Single Crystals ◽  
Room Temperature ◽  
Dielectric Studies ◽  
Floating Zone ◽  
Temperature Range

We herein report dielectric studies on Ca0.9Nd0.1Ti0.9Al0.1O3−δ single crystals grown by the optical floating zone technique in the temperature range from room temperature to 660 K.

scholarly journals TEMPERATURE DEPENDENCE OF OPTICAL TRANSMISSION OF GERMANIUM SINGLE CRYSTALS

2021 ◽  
pp. 177-186
Author(s):  
Александра Ивановна Иванова ◽  
Кристина Александровна Мариничева ◽  
Сергей Андреевич Третьяков ◽  
Алексей Михайлович Иванов ◽  
Сергей Вячеславович Молчанов ◽  
...  
Keyword(s):  
Single Crystals ◽  
Optical Transmission ◽  
Crystal Surface ◽  
Attenuation Coefficients ◽  
Temperature Changes ◽  
Temperature Range ◽  
Low Resistance ◽  
Donor And Acceptor ◽  
Helium Neon ◽  
Nanoscale Level

Проведены исследования оптического пропускания в диапазоне длин волн 2 - 14 мкм монокристаллов германия, легированных донорными и акцепторными примесями (удельное сопротивление германия 1 - 3 Ом⋅см), в интервале температур от 86 К до 523 К. Рассчитаны значения коэффициентов ослабления α для исследуемых кристаллов; минимальные значения коэффициентов ослабления (0,0015 - 0,0231 см) в интервале температур от 86 К до 323 К характерны для монокристаллов германия, легированных сурьмой, в диапазоне 2 - 11 мкм. Исследования показали, что низкие значения α и коэффициента пропускания на длине волны 3,39 мкм для кристаллов Ge: Sb и Ge: Bi позволяют применять эти низкоомные кристаллы германия для газовых гелий-неоновых лазеров при температурах от 86 К до 323 К. Исследованы температурные изменения геометрии поверхности кристалла на наноразмерном уровне. Показано, что нагрев кристаллического германия приводит к увеличению диффузного отражения излучения от поверхности. Сделан вывод о возможности использования низкоомных кристаллов германия, легированных сурьмой, в качестве элементов инфракрасной оптики в интервале температур 86 - 373 К. In this work, we investigated optical transmission in the wavelength range of 2-14 μm of low-resistance germanium crystals (1 - 3 Ω⋅cm) doped with donor and acceptor impurities in the temperature range from 86 K to 523 K. The values of the attenuation coefficients for investigated crystals are obtained. Minimum attenuation coefficients α of 0,0015 - 00231 cm in the temperature range from 86 K to 323 K are characteristic for germanium single crystals doped with antimony in the range 2,1-11 μm. Studies have shown that the low values of α and the transmittance at a wavelength of 3,39 pm for Ge: Bi and Ge: Sb crystals make it possible to use these low-resistance germanium crystals for gas helium-neon lasers at temperatures from 86 K to 323 K. The temperature changes in the geometry of the crystal surface are investigated at the nanoscale level. It is shown that heating crystalline germanium leads to an increase in the diffuse reflection of radiation from the surface. The possibility of using the low-resistance germanium crystals doped with antimony as elements of infrared optics in the temperature range 86 - 373 K has been demonstrated.

The Expansion upon Cooling of Thick Cu2O Films Grown on Copper Substrates

1966 ◽  
Vol 10 ◽  
pp. 234-239 ◽  
Author(s):  
T. F. Swank ◽  
K. R. Lawless
Keyword(s):  
Oxide Film ◽  
Single Crystals ◽  
Room Temperature ◽  
Anomalous Behavior ◽  
Temperature Changes ◽  
Bulk Single Crystals ◽  
Cu2o Films ◽  
Diffusion Rates ◽  
Copper Single Crystals ◽  
And Diffusion

AbstractDuring the course of catalytic experiments on bulk copper single crystals, several crystals were intentionally oxidized to form thick (6000 Å) Cu2O films on the copper substrates. These oxidized crystals were investigated by means of a high temperature chamber installed on a General Electric XRD-5 X-ray diffractometer. It was discovered subsequently that the lattice spacings of the Cu2O decreased upon heating and increased upon cooling. Bulk single crystals and polycrystals of copper were oxidized at 3 Torr of air for several hours. All of the oxidized crystals were examined with copper and chromium radiation and both showed similar results. Typical of the results was an oxidized (110) copper disc which showed a net contraction upon heating of 1% for the (110) Cu2O planes. This slightly oriented Cu2O film was distinguished because -it contracted on heating to 440°C from room temperature, then expanded from 440°-540°C, and then expanded again when cooled from 540°C to room temperature. CuO also was detected in the diffraction pattern and the CuO and copper spacings were behaving normally with the temperature changes. A polycrystal of Cu2O was'examined and that, of course, also acted normally as its temperature was varied. Borie and co-workers have reported and explained very nicely similar anomalous behavior for thinner (500 Å) (110) oriented Cu2O films grown on (110) copper substrates. They showed that the epitaxial forces would cause an oxide film grown at high temperatures to contract parallel to the metal interface and expand normal to the interface as the copper cools and contracts. The oxide would expand normal to the surface in. order to keep its unit cell volume constant.It is felt that epitaxial forces are not causing the anomalous behavior in the present work mainly because the 6000 Å of Cu2O is too thick for epitaxy to exert a meaningful force. The oxide film on the (110) copper was slightly (110) oriented but all of the Cu2O reflections behaved similarly. An additional reason to discount epitaxy is that this Cu2O film expanded upon heating from 440°-540°C. For these thick oxide films epitaxial forces do not seem to be the controlling factor; therefore, a point defect mechanism must be the cause. Changing oxidation and diffusion rates with temperature would produce various vacancy concentrations in the oxide layer and cause the spacings to vary.

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