The Magnetocaloric Effect And Critical Behavior Research Of Transition Metal Compounds

Magnetic refrigeration technology has been proved to be an environmentally safe refrigeration technology.The use of magnetic materials as a refrigerating medium,no damage to the ozone layer,not to aggravate the greenhouse effect.This paper mainly studies the critical behavior of materials related to the most important magnetothermal effect in the practical application of magnetic refrigeration,and explores the related parameters of its Curie temperature phase transition,which is of great significance to the practical application of materials.Binary chromium-sulfur compounds have rich magnetic transport and optical properties.These materials are likely to become ferromagnetic semi-metals in the future,which have excellent electron spin properties.Accurate critical values of ? and ? can be obtained by MAP and KF methods,and 8 can be obtained by critical isotherm analysis.The critical value obtained is very similar to that predicted by 3DIsng model theory.The forms of the interaction are J(r)?r-4.94,indicating that the ferromagnetic interaction in m-Cr5Te8 is between a long range interaction and a short range interaction.At the same time,measuring in H?50 kOe,-?SMmax of the m-Cr5Te8 is approximately equal to 16 mJ·cm-3·K-1.Heusler alloy compound Co2ZrSn has semi-metallic ferromagnetism and saturated magnetic moment?2?B/f.u.MAP and kouvel-fisher methods were used to verify the critical exponential ?,? and ? of the material,and these parameters were in good agreement with the scale rate.At the same time,it is proved by NS graph that using mean field model to describe the critical behavior of the material is the best choice.As the maximum magnetic entropy change-?SMmax is 0.57 J·kg-1·K-1 and RCP is 14.68 J·kg-11 when ?H=50 kOe.The result shows that the ? is less than 2,indicating that the long range spin interaction plays an important role in polycrystalline Co2ZrSn.