Magnetic phase transition and room-temperature magnetocaloric effects in (Al,M)Fe2B2 (M = Si, Ga) compounds

As the emerging ambient low-cost magnetic refrigeration system, the substitution effects on the magnetic properties and magnetocaloric effects in Al1-xSixFe2B2 (x= 0, 0.1, 0.2, 0.3) and Al1-yGayFe2B2 (y= 0.1 and 0.2) have been studied. The single phase is formed in a wide substitution composition region. All phase transitions in these compounds are of second-order and their Curie temperature (T-c) increases with more Si and Ga substitutions. For a field change of 5 T and 7 T, the maximum of entropy change (Delta S-max) of 4.9 J Kg(-1) K-1 and 6.3 J Kg(-1) K-1 are obtained and not dependent on the Si substitution amount in Al1-xSixFe2B2. As comparison, by Ga substitution, for the field change of 7 T and 5 T, the Delta S-max have been increased to 7.5 J Kg(-1) K-1 and 6 J Kg(-1) K-1 respectively. The tunable ambient T-c and considerable Delta S-max suggest that AlFe2B2-based compounds are potential low-cost ambient magnetic refrigeration candidates.