Tungsten-substituted double perovskite Ba2FeMo1-xWxO6 for enhanced magnetocaloric effects

摘要

Double perovskite materials Ba2FeMo1-xWxO6 (0.0 <= x <= 0.4) partially substituted with Tungsten (W) at the Molybdenum (Mo) site were prepared by the solid state reaction method and thoroughly investigated for structural, magnetic and magnetocaloric properties. Rietveld refined X-ray diffraction profiles were used to confirm the formation of cubic structure with Fm-3m space group in both the pristine as well as W-substituted samples. Upon increasing temperature, a single magnetic transition from ferromagnetic to paramagnetic phase was observed in each sample at its Curie temperature around which maximum magnetic entropy change could be obtained. A second order nature of the magnetic phase transition was established in all the samples with the help of Arrott plots and the universal master curve investigations and the magnetocaloric effect was obtained from the magnetic isotherms. Magnetocaloric effects estimated in terms of the maximum magnetic entropy change and temperature averaged entropy change (TEC) were enhanced with controlled W-substitution. Among the various compositions, sample with (x = 0.3) i.e., Ba2FeMo0.7W0.3O6 demonstrated a magnetic entropy change of 1.483 J/kgK and a TEC value of 2.74 J/kgK over a temperature span of 10 K under an applied magnetic field of 2.5 T. The results obtained in the present work clearly suggest that the investigated compounds can be customized for use in magnetic refrigeration technology.