scholarly journals Влияние морфологических дефектов на теплофизические свойства gamma-Gd-=SUB=-2-=/SUB=-S-=SUB=-3-=/SUB=-

2018 ◽  
Vol 60 (3) ◽  
pp. 482
Author(s):  
А.В. Сотников ◽  
В.В. Баковец ◽  
А.Ш. Агажанов ◽  
С.В. Станкус ◽  
Д.П. Пищур ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Single Crystal ◽  
Temperature Range ◽  
Ceramic Samples ◽  
Temperature Dependences ◽  
Morphological Defects ◽  
Large Heat

AbstractThe temperature dependences of the heat capacity ( C _ p ) and the thermal conductivity (κ) in the temperature range from 300 to 773 K of polycrystalline gadolinium sulfide samples (γ-GdS_ y ) with the deviation of the composition from the integer stoichiometric were studied. It was found that the thermal conductivity of gadolinium sulfides decreases monotonically and reaches 0.74 W/(m K) at T = 773 K for the composition y = 1.479, which is much lower than for the known single-crystal samples. The influence of morphological defects (boundaries of crystallites and dislocations) on the intensity of scattering of phonons is studied. It has been established that ceramic samples of gadolinium sulphides have a large heat capacity and a lower thermal conductivity, in comparison with monocrystalline samples of the same composition.

EXAMINATION OF THERMOPHYSICAL CHARACTERISTICS OF A HEAT-PROTECTIVE MATERIAL BASED ON FIBERGLASS DURING DESTRUCTION

2021 ◽  
pp. 91-97
Author(s):  
D.Ya. Barinov ◽  
◽  
S.Yu. Shorstov ◽  
M.G. Razmahov ◽  
A.I. Gulyaev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermophysical Properties ◽  
Thermal Effects ◽  
Space Technology ◽  
Muffle Furnace ◽  
Thermophysical Characteristics ◽  
Initial State ◽  
Protective Material ◽  
Temperature Dependences

When designing advanced samples of aviation and rocket and space technology, during the operation of which the temperature on the surface of the material can exceed the temperature of destruction, it is important to have an understanding of the values of thermophysical properties. The work investigates the thermophysical properties of fiberglass in the initial state and after the binder is burned out in a muffle furnace. The temperature dependences of thermal effects, heat capacity, thermal diffusivity and thermal conductivity were determined, density was measured, and thermogravimetric analysis was carried out. Using a stereomicroscope, the microstructure of the lateral cut of the samples was examined and its evolution was determined during the burning of the binder.

Thermal conductivity of the single-crystal monoisotopic 29Si in the temperature range 2.4–410 K

2013 ◽  
Vol 55 (1) ◽  
pp. 235-239 ◽  
Author(s):  
A. V. Inyushkin ◽  
A. N. Taldenkov ◽  
A. V. Gusev ◽  
A. M. Gibin ◽  
V. A. Gavva ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
Temperature Range

scholarly journals Heat capacity of lithium tungstate single crystal by DSC calorimetry data in the temperature range of 319-997 K

2021 ◽  
Vol 2057 (1) ◽  
pp. 012048
Author(s):  
N I Matskevich ◽  
V N Shlegel ◽  
A A Chernov ◽  
D A Samoshkin ◽  
S V Stankus ◽  
...  
Keyword(s):  
Heat Capacity ◽  
Phase Transitions ◽  
Single Crystal ◽  
Weight Control ◽  
Czochralski Technique ◽  
Temperature Range ◽  
First Time ◽  
Lithium Tungstate ◽  
Dsc Calorimetry ◽  
Calorimetry Data

Abstract The heat capacity of lithium tungstate single crystal (Li2WO4) was measured for the first time in the temperature range of 319-997 K. The experiments were carried out by DSC calorimetry. The Li2WO4 single crystal was first grown by low-temperature-gradient Czochralski technique with weight control. The temperature dependence of Li2WO4 heat capacity in the temperature range 319-997 K was monotonic. According to results of our studies, there were no phase transitions in Li2WO4 in the investigated temperature range.

Evidence of a Order-Disorder Transition in the Crystalline Phase of Cd6Yb, 1/1 cubic approximant of icosahedral Cd 5.7 Yb

2003 ◽  
Vol 793 ◽  
Author(s):  
N. Sorloaica ◽  
A. L. Pope ◽  
D. W. Winkler ◽  
Terry M. Tritt ◽  
V. Keppens ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Temperature Dependence ◽  
Transport Properties ◽  
Crystalline Phase ◽  
Thermal Transport ◽  
Hysteretic Behavior ◽  
Disorder Transition ◽  
Temperature Range ◽  
Thermal Transport Properties

ABSTRACTThe electrical and thermal transport properties (electrical resistivity, thermopower, heat capacity and thermal conductivity) of the crystalline phase of the binary Cd6Yb system has been measured over a temperature range from 10 K to 300 K. Evidence for a phase transition in Cd6Yb is observed in the electrical transport properties with distinct changes in the temperature dependence of the resistivity and thermopower around T ≈ 110K. An anomaly in the heat capacity and a thermal conductivity is also observed at this same temperature. Hysteretic behavior is not evident in the temperature dependence of any of the electrical and thermal transport properties. In addition, the elastic properties using resonant ultrasound (RUS) techniques have been investigated over a similar temperature range. A large “resonance dip” is observed in the RUS data at T ≈ 110K, which is indicative of some type of structural change in the crystalline material at this temperature. These data will be presented and discussed in context of the undergoes reversible order-disorder transition in the 1/1 cubic approximant at about 110 K, which makes the system very interesting compared to the quasicrystal phase Cd5.7Yb

scholarly journals THERMOPHYSICAL PROPERTIES OF ALLOY COMPOSITIONS (2Bi2O3∙B2O3)100-x(2Bi2O3∙3GeO2)x (x=0, 10, 50)

2021 ◽  
pp. 44-48
Author(s):  
S.I. Bananyarli ◽  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Phase Transitions ◽  
Thermal Resistance ◽  
Temperature Dependence ◽  
Thermophysical Properties ◽  
Chemical Bonds ◽  
Temperature Range ◽  
The Difference

The termophisical properties, namely, the temperature dependence of thermal conductivity, thermal resistance and heat capacity of the allays compositions (2Bi2O3∙B2O3)100-x (2Bi2O3∙3GeO2)x in the (300–600) K temperature range have ligated been invest. An increase in thermal conductivity χ(T) above 500 K is probably associated with the softening of alloys and the presence of blurred phase transitions, which are accompanied by partial breaking of chemical bonds. It was revealed that the heat capacity in alloys of the compositions (2Bi2O3∙B2O3)100-x (2Bi2O3∙3GeO2)x increases with an increase in the GeO2 concentration. In the studied samples, that showed their own disorder during solidification, the thermal conductivity is strongly reduced due to the enhancement of the anharmonicity of phonon – phonon interactions. İn turn a small "disorder" introduced by defects due to the difference in masses is not noticeable against the background of the huge "disorder" inherent in oxide substances

Thermal Conductivity of Single-Crystal ZrO2-Based Solid Solutions Stabilized with Scandium and Yttrium Oxides in the Temperature Range 50–300 K

2018 ◽  
Vol 60 (12) ◽  
pp. 2672-2677
Author(s):  
M. A. Borik ◽  
A. V. Kulebyakin ◽  
E. E. Lomonova ◽  
V. A. Myzina ◽  
P. A. Popov ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Single Crystal ◽  
Solid Solutions ◽  
Temperature Range

scholarly journals Measurement of Ex Vivo Liver, Brain and Pancreas Thermal Properties as Function of Temperature

Sensors ◽  
2021 ◽  
Vol 21 (12) ◽  
pp. 4236
Author(s):  
Ahad Mohammadi ◽  
Leonardo Bianchi ◽  
Somayeh Asadi ◽  
Paola Saccomandi
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Thermal Properties ◽  
Thermal Diffusivity ◽  
Ex Vivo ◽  
Pancreatic Tissue ◽  
Bioheat Transfer ◽  
Temperature Range ◽  
Ablative Techniques ◽  
The Brain

The ability to predict heat transfer during hyperthermal and ablative techniques for cancer treatment relies on understanding the thermal properties of biological tissue. In this work, the thermal properties of ex vivo liver, pancreas and brain tissues are reported as a function of temperature. The thermal diffusivity, thermal conductivity and volumetric heat capacity of these tissues were measured in the temperature range from 22 to around 97 °C. Concerning the pancreas, a phase change occurred around 45 °C; therefore, its thermal properties were investigated only until this temperature. Results indicate that the thermal properties of the liver and brain have a non-linear relationship with temperature in the investigated range. In these tissues, the thermal properties were almost constant until 60 to 70 °C and then gradually changed until 92 °C. In particular, the thermal conductivity increased by 100% for the brain and 60% for the liver up to 92 °C, while thermal diffusivity increased by 90% and 40%, respectively. However, the heat capacity did not significantly change in this temperature range. The thermal conductivity and thermal diffusivity were dramatically increased from 92 to 97 °C, which seems to be due to water vaporization and state transition in the tissues. Moreover, the measurement uncertainty, determined at each temperature, increased after 92 °C. In the temperature range of 22 to 45 °C, the thermal properties of pancreatic tissue did not change significantly, in accordance with the results for the brain and liver. For the three tissues, the best fit curves are provided with regression analysis based on measured data to predict the tissue thermal behavior. These curves describe the temperature dependency of tissue thermal properties in a temperature range relevant for hyperthermia and ablation treatments and may help in constructing more accurate models of bioheat transfer for optimization and pre-planning of thermal procedures.

scholarly journals Электропроводность монокристаллов MnGaInSе-=SUB=-4-=/SUB=- на переменном токе

2020 ◽  
Vol 46 (11) ◽  
pp. 19
Author(s):  
Н.Н. Нифтиев ◽  
Ф.М. Мамедов ◽  
М.Б. Мурадов
Keyword(s):  
Electrical Conductivity ◽  
Single Crystal ◽  
Frequency Dependence ◽  
Electric Current ◽  
Single Crystals ◽  
Activation Energies ◽  
Temperature Range ◽  
Temperature Dependences ◽  
Alternating Electric Current

The results of studying the frequency and temperature dependences of the electrical conductivity of MnGaInSe4 single crystals on alternating electric current are presented. It was found that in the temperature range of 295.5–360 K at frequencies of 2•104–106 Hz, the regularity σ ∼ fS (0.1≤ s≤1.0) holds for electrical conductivity. It is shown that in the MnGaInSe4 single crystal the frequency dependence of electrical conductivity can be explained using the multiplet model, and the conductivity in these single crystals is characterized by a band-hop mechanism. Based on the dependences log σ ∼ 103/T, the activation energies are determined.

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