Search

Rare earth-based materials with a large magneto-caloric (MC) effect have aroused significant research interest due to their potential application for cryogenic magnetic refrigeration (MR) technology. In this study, the Cu site Zn-substituted Dy2BaCu1−xZnxO5 oxides were synthesized and systematically investigated concerning the structural, magnetic phase transition, and MC properties. All the Dy2BaCu1−xZnxO5 oxides were found to be single-phased with an orthorhombic crystal structure (space group Pnma). With the increase of Zn content in the Dy2BaCu1−xZnxO5 oxides, the magnetic phase transition (MPT) temperature decreases gradually from 12.1 K to 2.1 K and the nature of MPT changes from first-order to second-order type. Moreover, Zn substitution leads to enhanced MC performance. The maximum magnetic entropy changes, temperature-averaged entropy changes with 5 K-lift, and relative cooling powers under the magnetic field change of 0–70 kOe were evaluated to be 8.49 J/kgK, 9.67 J/kgK and 13.23 J/kgK, 8.38 J/kgK, 9.29 J/kgK, and 13.03 J/kgK and 227.43 J/kg, and 283.63 J/kg and 343.04 J/kg for Dy2BaCu0.75Zn0.25O5, Dy2BaCu0.5Zn0.5O5 , and Dy2BaCu0.25Zn0.75O5, respectively. The observed tunable MPT and enhanced MC performances indicate that the present Dy2BaCu1−xZnxO5 oxides have potential for practical cryogenic MR applications. [ABSTRACT FROM AUTHOR]

The magnetocaloric effect (MCE) is currently intensively investigated in various rare earths ( RE )-containing magnetic solids, not only for developing appropriate magnetocaloric materials (MCMs) for cryogenic magnetic cooling but also for deepening our understanding into the inherent physical properties of these materials. Here, we provide a systematic experimental investigation into a series of new RE 2 CuTiO 6 ( RE = Dy, Ho, Er) double-perovskite (DP) oxides regarding the structural and magnetic properties, especially for their cryogenic MCE and magnetic-phase transition (MPT). All of these RE 2 CuTiO 6 oxides crystallize in a B -site-ordered hexagonal DP-type structure with the symmetry of the crystallographic space group P 6̅ m 2. These DP oxides exhibit magnetic ordering, with MPT temperatures of approximately 2.7, 2.2, and 2.7 K for Dy 2 CuTiO 6 , Ho 2 CuTiO 6 , and Er 2 CuTiO 6 , respectively. The magnetocaloric performances of the RE 2 CuTiO 6 DP oxides were characterized by the peak values of magnetic entropy change, the temperature-averaged magnetic entropy change (5K-lift), and relative cooling powers. These magnetocaloric parameters were deduced to be 18.7/17.9 J/kgK and 298.2 J/kg for Dy 2 CuTiO 6 , 12.5/12.2 J/kgK and 273.9 J/kg for Ho 2 CuTiO 6 , and 13.8/12.9 J/kgK and 188.4 J/kg for Er 2 CuTiO 6 under a magnetic field change of 0-5 T. These values are comparable to those of most reported RE -containing magnetocaloric materials, indicating that these RE 2 CuTiO 6 DP oxides are promising candidates for cryogenic magnetic cooling applications.