Large magnetic entropy change in TbAl₂ (Tb_0.4Gd_0.6)Al₂

Rare-earth intermetallic compounds (Tb_1-xGd_x)Al₂, have been successfully fabricated and characterized. Large magnetic entropy change, ΔS_M, was observed in these alloys. The maximum - ΔS_M( = 14.3 J/kg K) is achieved in the TbAl₂ alloy at its Curie temperature, T_C = 105 K, with a 5 T magnetic field change. It is shown that the alloys are very soft magnetic alloys. The magnetic entropy change is thus completely reversible in the whole temperature range of 80-180 K. An interesting feature in (Tb_1-xGd_x)Al₂ compounds is that the Curie temperature can be easily shifted by tuning the composition. These alloys, therefore, appear to be an attractive material candidate for realizing the active magnetic regenerator magnetic refrigerator consisting of eight stages, as suggested by K. A. Gschneidner, Jr. and V. K. Percharsky. [Rare Earth: Science, Technology, and Applications III, edited by R. G. Bautista, C. O. Bounds, T. W. Ellis, and B. T. Kilbourn (The Minerals, Metals and Materials Society, 1997), p. 209.]