Predictable magnetocaloric effect in the Ce2Fe17−xMnxHy hydrides

Hydrogenation of Ce2Fe17−xMnx, x = 0–1.7 compounds results in an increase of the peak entropy change −ΔSM about by half. The maximum entropy change −ΔSM for the Ce2Fe17H2.1 ferromagnet is 4.9 J/kg K at T = 330 K in a field of 5 T. In the Ce2Fe17−xMnxHy systems with the ground ferromagnetic state and high-temperature antiferromagnetic one, the peak entropy change −ΔSM increases when the temperatures of the magnetic phase transitions ΘT, TN approach each other with growing the H content. By means of extrapolation of the (TN–ΘT) difference to the zero value one can obtain the greatest possible value of the maximum entropy change −ΔSM in the system. A superposition of the −ΔSM(T) maxima at ΘT and TN in the case of compounds which have two points of magnetic phase transitions causes a drastic increase of the relative cooling power, as compared with compounds having only one magnetic phase transition at TN or TC.

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► Hydrogenation of Ce2Fe17−xMnx causes increase of MCE about by half.
► MCE exhibits peaks at the temperatures ΘT, TN, TC of magnetic phase transitions.
► Extrapolation of (TN–ΘT) to zero predicts the greatest value of MCE in a system.
► The maximum obtained entropy change is 4.9 J/kg K at T = 330 K for Ce2Fe17H2.1.
► A superposition of MCE maxima at ΘT and TN causes drastic increase of RCP.