Tailoring cryogenic thermal conductivity in EuTiO3-based magnetic refrigeration materials

As one of the core components of a magnetic refrigerator, magnetic refrigeration materials are expected to have not only a considerable magnetocaloric effect but also excellent thermal conductivity . The poor thermal conductivity of many competitive oxide-based magnetic refrigerants, exemplified by EuTiO 3 -based compounds, acts as a major limitation to their practical application. Therefore, improving the thermal conductivity of magnetic refrigeration materials has become a research emphasis of magnetic refrigeration in recent years. In this work, a series of EuTiO 3 (ETO)/Cu composites with different copper additives was prepared using a solid-phase reaction method by introducing appropriate amounts of copper powder. The influence of the introduction of copper on the phase composition, microstructure, thermal conductivity , and magnetocaloric effect of the composites was systematically investigated. Unexpectedly, the thermal conductivity of the composites is enhanced by up to 260% due to copper addition, accompanied by only a 5% decrease in magnetic entropy change and refrigerating capacity. Copper additive forms localized thermal conductive networks and promotes the densification process , resulting in significantly enhanced thermal conductivity of the composites. This work demonstrates the feasibility of improving the thermal conductivity of oxide-based magnetic refrigeration materials by introducing highly thermally conductive substances.