ACCURATE DETERMINATION OF THE MAGNETOCALORIC PARAMETERS OF LaFeCoSi COMPOUNDS

摘要

Four samples of magnetocaloric compounds of general formula La(Fe,Co,Si)_(13) with transition temperaturesrnbetween 253 K and 307 K have been characterized. A precise determination has been obtained for the adiabatic temperature increment, ΔT_(ad), and the isothermal entropy change, ΔS_T, under various field changes between 0 and 5 Tesla. Field dependent heat capacities have been measured with adiabatic calorimetry. Direct measurements of ΔS_T and ΔT_(ad) have been done under quasistatic field changes. Results from the entropy derived functions have also been used for indirect determinations of the magnetocaloric parameters. The results from direct and indirect determinations give an excellent match and also agree with the values of ΔS_T derived from magnetization measurements.