La(Fe,Si)13-based magnetic refrigerants obtained by novel processing routes

The structure and magnetic properties of LaFe_13−xSi_x and Co-substituted LaFe_11.8−xCo_xSi_1.2 alloys prepared by melt spinning, as well as of LaFe_11.57Si_1.43H_x hydrides prepared by reactive milling are investigated. The hysteresis in the temperature- and field-induced phase transitions is significantly reduced as compared with conventional bulk alloys, which makes these materials very attractive for magnetic refrigerant applications. The unusual combination of features characteristic of first- and second-order phase transitions in the La(Fe,Si)₁₃-based compounds is discussed on the basis of density-functional electronic structure calculations.