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Tb 4 Gd 1 Si 2.035 Ge 1.935 Mn 0.03 alloy was prepared by arc melting followed by annealing at 1193 K for 168 h. Structural characterizations reveal that monoclinic (Tb, Gd) 5 Si 2 Ge 2 -type phase, secondary phase with orthorhombic 5-4 type structure and hexagonal 5-3 type structure coexist in the alloy. The paramagnetic Curie temperature ( θ p ) is 120 K, indicating that the dominant exchange interaction is ferromagnetic or ferrimagnetic. That the thermal hysteresis of 13 K between heating and cooling and the negative slopes of Arrott plots derived from M – H curves between 116 K and 170 K confirm a typical first-order magnetic transition from ferromagnetism to paramagnetism occurs. The maximum magnetic entropy changes of the Tb 4 Gd 1 Si 2.05 Ge 1.95 Mn 0.03 alloy for magnetic field changes of 0–1 T, 0–2 T, 0–3 T, 0–4 T and 0–5 T are about 3.3, 8.6, 14.0, 18.9 and 22.4 J/kg K, respectively. And the effective refrigeration capacity (RC eff ) value is 231 J/kg with a subtracted magnetic hysteresis loss of 30 J/kg for a magnetic field change from 0 to 5 T. Large −Δ S M and RC eff suggest that Tb 4 Gd 1 Si 2.035 Ge 1.935 Mn 0.03 alloy is an attractive potential magnetocaloric material working in the vicinity of 143 K. |
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