Mn doping effects on the structural, magnetic and magnetocaloric properties in Ho2O3 powders

Abstract We have investigated the structural, magnetic and magnetocaloric properties of the Mn-doped Ho2-xMnxO3 (x = 0.00, 0.05 and 0.10) powders prepared using sol-gel technique. X-ray diffraction (XRD) analysis using Rietveld refinement has shown that all the samples crystallize in the bixbyite structure. Scanning electron microscopy has shown that the powders are chemically homogeneous. All samples undergo an antiferromagnetic order at low temperature (≤4 K). The substitution of Mn leads to a slight increase of Neel temperature and decrease in magnetization. Hysteresis curves highlight a second-order feature of phase transition and a reversible magnetocaloric effect. Under a magnetic field change of 20 kOe, the maximum value of the isothermal magnetic entropy change (−ΔSMax) decreases from 16.5 J/kg· K (x = 0.00) to 8.64 J/kg·K (x = 0.10). The large magnitude of (−ΔSMax) as well as the absence of hysteresis loss make Ho2-xMnxO3 a promising material for magnetic refrigeration at low temperature range.