Structural, magnetic and magnetocaloric properties in distorted RE 2NiTiO6 double perovskite compounds

Abstract

The magnetocaloric effect based Magnetic refrigeration (MR) was considered a novel energy-efficient and environmentally benign cooling method. However, the lack of suitable magnetic solids has slowed the development of its practical applications. We herein fabricated the RE 2NiTiO6 (RE = Gd, Tb and Ho) double perovskite (DP) compounds and systematically determined their structural, magnetic and magnetocaloric properties by experimental determination and density functional theory calculations, in which the Gd2NiTiO6 was realized to exhibit promising cryogenic magnetocaloric performances. The results indicated that all the RE 2NiTiO6 DP compounds crystallized in a distorted monoclinic structure with P21/n space group and underwent a second order type magnetic phase transition around 4.3, 4.5 and 3.9 K, for Gd2NiTiO6, Tb2NiTiO6 and Ho2NiTiO6, respectively. The magnetocaloric performances were checked by the parameters of maximum magnetic entropy change and relative cooling power, which are 31.28 J·kg−1·K−1 and 242.11 J·kg−1 for Gd2NiTiO6, 13.08 J·kg−1·K−1 and 213.41 J·kg−1 for Tb2NiTiO6, 11.98 J·kg−1·K−1 and 221.73 J·kg−1 for Ho2NiTiO6 under the magnetic field change of 0–50 kOe, respectively. Evidently, the Gd2NiTiO6 compound exhibit promising magnetocaloric performances and therefore is of potential for practical cryogenic MR applications.