Cryogenic magnetic properties and magnetocaloric effects in orthorhombic EuZrO3-based ceramics

Cryogenic refrigeration plays a key strategic role in many scientific frontiers and engineering technology fields. Magnetic refrigeration has the advantages of intrinsically high efficiency and independence from liquid helium, and has attracted great attention in cryogenic refrigeration. In recent years, larger low-field magnetocaloric effect (MCE) at lower temperatures have been a continuing pursuit of materials researchers in related fields. Herein, an orthorhombic-structured EuZrO 3 polycrystal and two derivatives were prepared via a modified solid-phase reaction approach. Experimental results reveal that EuZrO 3 undergoes a paramagnetic-antiferromagnetic phase transition near the liquid helium temperature. When part of Zr element is substituted by Nb or Ta, the phase transition temperature decreases to 3.8 K, below which the compounds still behave antiferromagnetically ordered. However, the MCEs of the compounds at low temperatures and low fields are significantly enhanced, which may be attributed to the enhanced ferromagnetic interaction. The maximum magnetic entropy change ( − Δ S M max ) and refrigeration capacity of EuZr 0.875 Nb 0.125 O 3 and EuZr 0.875 Ta 0.125 O 3 are both improved by more than 20 % over EuZrO 3 under magnetic field change of 0–1 T. It is worth noting that the magnetic entropy change values at 2.5 K are improved by a factor of more than four over that of EuZrO 3 for these two derivative compounds.