Тепловые и магнитокалорические свойства манганитов La-=SUB=-0.7-=/SUB=-Sr-=SUB=-0.3-x-=/SUB=-Ba-=SUB=-x-=/SUB=-MnO-=SUB=-3-=/SUB=-

The results of a study of the effect of partial substitution of Sr2+ ions by Ba2+ ions on the thermophysical and magnetocaloric properties of manganite La0.7Sr0.3-xBaxMnO3 (x = 0; 0.02; 0.05 and 0.10) in the temperature range 100-400 K and in a magnetic field up to 1.8 T. It is shown that such a substitution leads to a significant decrease in TC. In the behaviour of the thermal diffusivity (T) and thermal conductivity (T) near TС, minima were found that are associated with both the scattering of phonons by local distortions of the crystal lattice and by spin fluctuations. The absolute values of thermal conductivity decrease with an increase in the disorder parameter. The magnetocaloric effect exhibits a weak dependence on the substitution level (x).

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Thermal Conductivity and Thermal Diffusivity

10.31399/asm.tb.mlt.t62860133 ◽

1983 ◽

pp. 133-161

Author(s):

J. G. Hust

Keyword(s):

Magnetic Field ◽

Thermal Conductivity ◽

Heat Treatment ◽

Thermal Diffusivity ◽

Heat Transport ◽

Measurement Methods ◽

Basic Principles ◽

Qualitative And Quantitative ◽

Effects Of Temperature ◽

Theoretical Results

Abstract This chapter presents basic principles and the theoretical results of heat transport in solids. Thermal conductivity and thermal diffusivity are the principal properties discussed. Discussions are also included on the effects of temperature, magnetic field, and metallurgical variations caused by composition, processing, and heat-treatment differences. Numerous graphs illustrate the qualitative and quantitative effects of these variables. Measurement methods and associated accuracies and pertinent empirical correlations are presented.

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Processing and Generalization of Experimental Data on Thermal Diffusivity and Thermal Conductivity of Magnetic Fluids Depending on the Impact of the Magnetic Field

Vestnik Tambovskogo gosudarstvennogo tehnicheskogo universiteta ◽

10.17277/vestnik.2021.02.pp.231-237 ◽

2021 ◽

Vol 27 (2) ◽

pp. 231-237

Author(s):

D. S. Dzhuraev

Keyword(s):

Magnetic Field ◽

Experimental Data ◽

Thermal Conductivity ◽

Thermal Diffusivity ◽

Iron Powder ◽

Experimental Studies ◽

Magnetic Fluids ◽

Transformer Oil ◽

The Impact ◽

The Magnetic Field

The paper presents the results of experimental studies of the thermal diffusivity and thermal conductivity of magnetic fluids based on transformer oil, depending on the effect of a magnetic field in the range of B = 1.59...3.866 mT, and the addition of iron powder 0.1...0.3 g with an interval of 0.05 g. Equations were obtained for calculation with a certain fraction of error in thermal diffusivity and thermal conductivity of unexplored magnetic fluids.

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