Effect of Ti substitution on structural, magnetic and magnetocaloric properties in double perovskites Gd2NiMn1-xTixO6 (0 ≤ x ≤ 1)

Abstract

Magnetic refrigeration by utilizing the magnetocaloric effect of magnetic solid materials has been expected to be a green energy technology. In this work, double perovskite oxides Gd2NiMn1-xTixO6 (0 ≤ x ≤ 1) were successfully synthesized via the traditional solid-state reaction method. Structural, magnetic and cryogenic magnetocaloric properties of the prepared samples were experimentally investigated. The magnetic measurements indicate that the ferromagnetic phase is progressively suppressed by Ti substitution in Gd2NiMn1-xTixO6 owing to the dilution effect of nonmagnetic Ti4+ with 3d0 configuration. In addition, the two vital parameters of magnetic entropy change and refrigeration capacity for magnetocaloric properties have been calculated and analyzed. The values of the maximum magnetic entropy change and refrigeration capacity show a similar change regularity, which decrease firstly from 23.33 J kg−1 K−1 (334.68 J kg−1) at x = 0 to 13.70 J kg−1 K−1 (226.07 J kg−1) at x = 0.4, and then increase significantly to 27.57 J kg−1 K−1 (360.02 J kg−1) at x = 1 under ΔH = 6 T. A possible mechanism for the effect of Ti substitution on the magnetic and magnetocaloric properties of Gd2NiMn1-xTixO6 has been proposed. The present work indicates that Gd2NiMn1-xTixO6 could be important candidates for magnetic refrigeration application.