Tuning the structural and magnetocaloric properties of Gd_5Si_2Ge_2 with Nd substitution

摘要

Structural and magnetocaloric properties of Nd substituted Gd_(5-x)Nd_xSi_2Ge_2 with x = 0.05, 0.1, and 0.2 have been investigated. The composition with x = 0.05 crystallizes in monoclinic Gd_5Si_2Ge_2 structure with P112_1/a space group and undergoes a first order phase transition with a Curie temperature of 275 K. With increase in Nd content to x = 0.1, the compound is found to stabilize in orthorhombic Gd_5Si_4 phase with Pnma space group. The compounds with x = 0.1 and 0.2 undergoes a second order magnetic transition at 300 K and 293 K, respectively. Temperature variation of maximum entropy change for Gd_(5-x)Nd_xSi_2Ge_2 alloys with x = 0.05, 0.1, and 0.2 are 7.9, 3.7, and 3.2 J/kg K, respectively, for a field change of 20 kOe, and 12.8, 7.6, and 7.2 J/kg K, respectively, for 50 kOe. A large relative cooling power of 295, 205, and 188 J/kg are obtained for x = 0.05, 0.1, and 0.2, respectively, fulfilling the required criteria for a potential magnetic refrigerant in the room temperature regime.