Near room temperature magnetic entropy changes in as-cast Gd100−xMnx (x = 0, 5, 10, 15, and 20 at.%) alloys

A series of Gd100−xMnx (x = 0, 5, 10, 15, and 20 at.%) alloys were prepared by arc-melting. The Curie temperature (TC) associated with the ferromagnetic–paramagnetic transitions, derived from M–T curves, show decrease in TC for as-cast alloys (∼279 K) as compared to as-cast Gd (∼292 K). No appreciable decrease in the |ΔSM|max values ∼4.6 J/kg K (0–2 T) and ∼8.6 J/kg K (0–5 T) were observed upon alloying Gd with Mn up to x ≤ 15 at.%. Refrigerant capacity (q) showed negligible variation ∼195 J/kg (0–2 T) and ∼450 J/kg (0–5 T) with increasing Mn (up to x ≤ 15 at.%) content. Similar values of |ΔSM|max and q coupled with ∼13 K decrease in TC for as-cast Gd100−xMnx (0 ≤ x ≤ 15) alloys as compared to Gd, suggests expansion of working temperature region of Gd upon alloying with Mn up to 15 at.%. Low cost, adjustable TC, favorable magnetocaloric properties make Gd100−xMnx alloys potential candidates as second-order transition based magnetic refrigerants for near room temperature air-conditioning and magnetic refrigeration.

Research highlights▶ Binary alloying of Gd with Mn decreases the Curie temperature for as-cast Gd100−xMnx (x ≤ 20 at.%) alloys, as compared to as-cast Gd, by ∼13 K. ▶ No appreciable decrease in the maximum magnetic entropy change (|ΔSM|max) and refrigeration capacity (q) were observed upon alloying Gd with up to 15 at.% Mn. ▶ Similar values of |ΔSM|max (∼4.6 and 8.6 J/kg K at 0–2 and 0–5 T, respectively) and q (∼195 and 450 J/kg at 0–2 and 0–5 T, respectively) coupled with ∼13 K decrease in TC for as-cast Gd100−xMnx (0 ≤ x ≤ 15) alloys as compared to Gd, suggests expansion of working temperature region of Gd upon alloying with Mn up to 15 at.%. ▶ Low cost, adjustable TC, favorable magnetocaloric properties make Gd100−xMnx (0 ≤ x ≤ 15) alloys potential candidates as second order transition based magnetic refrigerants for near room temperature air-conditioning and magnetic refrigeration.