Effect of B-doping on the structure and magnetocaloric properties of plate-shaped La0.6Pr0.4Fe11.4Si1.6Hx sintered in high-pressure H2 atmosphere

Plate-shaped La0.6Pr0.4Fe11.4Si1.6B0.2Hx bulk samples have been achieved with sintering in a high-purity H2 atmosphere at 50 MPa. The effect of B-doping on the structure, magnetism and magnetocaloric properties of the plate-shaped hydrides has been systematically explored. The results show that B-doping unfavorably leads to a remarkable increase of Fe2B during the sintering process and has not helped much in the 1:13 phase stabilization and/or in the magnetocaloric properties. At 340 K, a high-density sintered thin plate shows a large magnetic-entropy change ΔSm of 16.2 J/kg·K and a favorable small hysteresis of 0.6 J/kg for a field change from 0 to 5 T. High-resolution X-ray microtomography analysis shows that micropores exist in the thin plates causing a porosity of 0.26% and leading to a remarkable reduction of the hysteresis. This work opens an effective route for synthesizing thin magnetic refrigerants of La(Fe, Si)13Hx hydrides.