Low hysteresis and large room temperature magnetocaloric effect of Gd5 Si2.05−x Ge1.95−x Ni2x (2x = 0.08, 0.1) alloys

• Main Authors: Ramanujan, Raju Vijayaraghavan, Zhong, X. C., Min, J. X., Liu, Z. W., Zheng, Z. G., Zeng, D. C., Franco, V.
• Other Authors: School of Materials Science & Engineering
• Format: Article
• Language: English
• Published: 2014
• Subjects: Materials Science and Engineering
• Online Access: https://hdl.handle.net/10356/100205; http://hdl.handle.net/10220/18617
• Institution: Nanyang Technological University

Gd5Si2.05− x Ge 1.95− x Ni 2 x (2x = 0.08, 0.1) alloys were prepared by arc melting followed by annealing at 1273 K for 96 h. Mixed monoclinic Gd5Si2 Ge 2-type phase, orthorhombic Gd5Si4-type phase, and a small amount of Gd5Si3-type phase were obtained in these alloys. Gd5Si2.01 Ge 1.91 Ni 0.08 alloy undergoes a second-order transition (T C) around 300 K, whereas Gd5Si2 Ge 1.9 Ni 0.1 alloy exhibits two transitions including a first-order transition (T C ІІ) at ∼295 K and second-order transition (T C І) at ∼301 K. Ni substitution can effectively reduce the thermal hysteresis and magnetic hysteresis while maintaining large magnetic entropy change. The maximum magnetic entropy changes (|ΔSM max|) of Gd5Si2.05− x Ge 1.95− x Ni 2 x alloys with 2x = 0.08 and 0.1 are 4.4 and 5.0 J kg−1 K−1, respectively, for 0–2 T, and are 8.0 and 9.1 J kg−1 K−1, respectively, for 0–5 T. Low hysteresis performance and relatively large magnetic entropy change make these alloys favorable for magnetic refrigeration applications.