scholarly journals Рассеяние фононов на парамагнитных ионах европия и самария в феррите висмута

2020 ◽  
Vol 62 (7) ◽  
pp. 1137
Author(s):  
Р.Г. Митаров ◽  
С.Н. Каллаев ◽  
А.М. Бакмаев ◽  
С.А. Резниченко ◽  
А.Т. Темиров
Keyword(s):  
Thermal Conductivity ◽  
Rare Earth ◽  
Thermal Diffusivity ◽  
Temperature Dependence ◽  
Wide Temperature Range ◽  
Bismuth Ferrite ◽  
Resonance Scattering ◽  
Phonon Thermal Conductivity ◽  
Temperature Range ◽  
The Rare Earth

The temperature dependence of the thermal diffusivity and thermal conductivity of the multiferroics BiFeO3, Bi0.90Sm0.10FeO3 and Bi0.90Еu0.10FeO3 is studied. It was found that the substitution of bismuth ions by the rare-earth europium and samarium ions in bismuth ferrite leads to a decrease in phonon thermal conductivity in a wide temperature range. It was established that the decrease in the thermal conductivity of bismuth ferrite is due to resonance scattering of phonons at paramagnetic levels of europium and samarium ions.

scholarly journals Влияние мультиплетных уровней Sm-=SUP=-3+-=/SUP=- и Eu-=SUP=-3+-=/SUP=- на теплоемкость мультиферроика BiFeO-=SUB=-3-=/SUB=-

2021 ◽  
Vol 63 (6) ◽  
pp. 763
Author(s):  
Р.Г. Митаров ◽  
С.Н. Каллаев ◽  
З.М. Омаров ◽  
О.М. Назарова ◽  
Л.А. Резниченко
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Rare Earth ◽  
Specific Heat ◽  
Temperature Dependence ◽  
Bismuth Ferrite ◽  
Rare Earth Ions ◽  
Phonon Thermal Conductivity ◽  
Additional Heat ◽  
Schottky Effect

The temperature dependence of the heat capacity of the multiferroics BiFeO3, Bi0.90Sm0.10FeO3, and Bi0.90Eu0.10FeO3 has been studied. It was found that the substitution of europium and samarium ions for bismuth ions in bismuth ferrite leads to the appearance of an additional heat capacity component due to transitions of 4f - electrons of rare earth ions to higher levels of the multiplet. A connection is established between the decrease in phonon thermal conductivity and the Schottky effect for the specific heat.

scholarly journals Phonon hydrodynamics and ultrahigh–room-temperature thermal conductivity in thin graphite

Science ◽  
2020 ◽  
Vol 367 (6475) ◽  
pp. 309-312 ◽  
Author(s):  
Yo Machida ◽  
Nayuta Matsumoto ◽  
Takayuki Isono ◽  
Kamran Behnia
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Phonon Dispersion ◽  
High Conductivity ◽  
Temperature Range ◽  
A Value ◽  
Out Of Plane ◽  
Intimate Link

Allotropes of carbon, such as diamond and graphene, are among the best conductors of heat. We monitored the evolution of thermal conductivity in thin graphite as a function of temperature and thickness and found an intimate link between high conductivity, thickness, and phonon hydrodynamics. The room-temperature in-plane thermal conductivity of 8.5-micrometer-thick graphite was 4300 watts per meter-kelvin—a value well above that for diamond and slightly larger than in isotopically purified graphene. Warming enhances thermal diffusivity across a wide temperature range, supporting partially hydrodynamic phonon flow. The enhancement of thermal conductivity that we observed with decreasing thickness points to a correlation between the out-of-plane momentum of phonons and the fraction of momentum-relaxing collisions. We argue that this is due to the extreme phonon dispersion anisotropy in graphite.

scholarly journals Thermophysical properties of BiFeO3/REE multiferroics in a wide temperature range

2020 ◽  
Vol 10 (01n02) ◽  
pp. 2060019
Author(s):  
Sidek Khasbulatov ◽  
Suleiman Kallaev ◽  
Haji Gadjiev ◽  
Zairbek Omarov ◽  
Abumuslim Bakmaev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Capacity ◽  
Rare Earth ◽  
High Temperature ◽  
Thermal Diffusivity ◽  
Rare Earth Elements ◽  
Wide Temperature Range ◽  
Thermophysical Properties ◽  
Multiferroic Bifeo ◽  
Comprehensive Study

The paper presents the results of a comprehensive study of the thermophysical properties (thermal conductivity, thermal diffusivity, heat capacity) of high-temperature multiferroic BiFeO3 modified with rare-earth elements (REEs) (La, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Lu). The regularities of the formation of the mentioned characteristics were established. The assumptions about the nature of the observed phenomena were suggested.

Thermal conductivity and thermal diffusivity coefficients of 12Kh18N10T stainless steel in a wide temperature range

2008 ◽  
Vol 46 (5) ◽  
pp. 731-733 ◽  
Author(s):  
S. V. Stankus ◽  
I. V. Savchenko ◽  
A. V. Baginskii ◽  
O. I. Verba ◽  
A. M. Prokop’ev ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Stainless Steel ◽  
Thermal Diffusivity ◽  
Wide Temperature Range ◽  
Temperature Range

Magnetic properties of rare earth chromium borates at high temperatures

2021 ◽  
pp. 166-170
Author(s):  
O.K. Kuvandikov ◽  
◽  
N.I. Leonyuk ◽  
V.V. Malsev ◽  
M.M. Kuzmin ◽  
...  
Keyword(s):  
Magnetic Properties ◽  
Magnetic Susceptibility ◽  
Rare Earth ◽  
Temperature Dependence ◽  
High Temperatures ◽  
Wide Temperature Range ◽  
Magnetic Moments ◽  
Chemical Formula ◽  
Temperature Range ◽  
Curie Temperatures

Temperature dependence of the magnetic susceptibility has been studied for rare-earth borates NdCr3(BO3)4, SmCr3(BO3)4 and LuCr3(BO3)4 by the Faradey method in the wide temperature range (300-1200 K). The dependence for each phase follows the Curi - Weis law. The Curie temperatures, Neel temperatures and magnetic moments corresponding to the chemical formula of the crystals, have been found.

Optical Determination of Thermal Conductivity with a Plane Source Technique

1968 ◽  
Vol 23 (5) ◽  
pp. 682-686 ◽  
Author(s):  
Silas E. Gustafsson ◽  
Nils-Olov Halling ◽  
Rolf A. E. Kjellander
Keyword(s):  
Thermal Conductivity ◽  
Thermal Diffusivity ◽  
Temperature Dependence ◽  
Theoretical Approach ◽  
Experimental Results ◽  
Plane Source ◽  
Melting Points ◽  
Temperature Range ◽  
Optical Determination

The thermal conductivity and the thermal diffusivity of the three alkali nitrates LiNO3 , RbNO3 and CsNO3 have been measured over a temperature range between 50° and 100 °C above their melting points. Any temperature dependence of the thermal conductivity cannot be established for any of the investigated liquids but the results indicate that it must be less than 10-3 °C-1. The experimental results are compared with the conductivities which can be calculated with already excisting theories. A somewhat modified theoretical approach is suggested for estimating the thermal conductivity, where no adjustable parameters are being used. The experimental and theoretical values at the melting points agree within about 10 percent.

Thermodynamic properties of the rare earth borides and carbides a wide temperature range

1993 ◽  
Vol 201 (1-2) ◽  
pp. 127-128 ◽  
Author(s):  
A.S. Bolgar ◽  
V.B. Muratov ◽  
A.V. Blinder ◽  
A.I. Kryklya ◽  
A.P. Suodis
Keyword(s):  
Rare Earth ◽  
Thermodynamic Properties ◽  
Wide Temperature Range ◽  
Temperature Range ◽  
The Rare Earth

Rare earth magnets for applications over a wide temperature range

1993 ◽  
Vol 124 (3) ◽  
pp. 325-329 ◽  
Author(s):  
M. Hasegawa ◽  
K. Uchida ◽  
Y. Nozawa ◽  
M. Endoh ◽  
S. Tanigawa ◽  
...  
Keyword(s):  
Rare Earth ◽  
Wide Temperature Range ◽  
Temperature Range
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