Structural, magnetic and magnetocaloric properties in the rare earth ruthenate RE3RuO7 (RE = Pr, Nd, Gd and Tb) oxides with fluorite related structure

Abstract

The magnetic refrigeration (MR) based on magnetocaloric effect (MCE) is a key technique, since it possesses ideally higher performance than the traditional gas compression technology. However, the lack of MR materials with excellent MCE performance is a bottle-neck for practical MR applications. Herein, we systematically report the structural properties using powder X-ray diffraction and scanning electron microscope as well as the magnetic and magnetocaloric properties through the magnetization measurements of four rare-earth (RE) ruthenate RE3RuO7 (RE = Pr, Nd, Gd and Tb) compounds. Light RE-based Pr3RuO7 and Nd3RuO7 compounds form an orthorhombic Cmcm structure, while heavy RE based Gd3RuO7 and Tb3RuO7 compounds crystallize in an orthorhombic P21nb structure. The magnetic phase transition of all the present compounds are confirmed to be of the first-order type with TN of 52, 15, 11 and 12 K for Pr3RuO7, Nd3RuO7, Gd3RuO7 and Tb3RuO7 compounds, respectively. The related MCE parameters including the maximum isothermal magnetic entropy change, temperature-averaged entropy change (5 K lift), and refrigerant capacity with the magnetic field change of 0–5 T were computed to be 1.35 J/kgK, 1.31 J/kgK, and 27.4 J/kg for Pr3RuO7, to be 2.18 J/kgK, 2.04 J/kgK, and 25.6 J/kg for Nd3RuO7, to be 8.12 J/kgK, 7.90 J/kgK, and 124.6 J/kg for Gd3RuO7, and to be 7.78 J/kgK, 7.49 J/kgK, and 128.8 J/kg for Tb3RuO7, respectively.