Comparison of two methods for achieving table-like magnetic entropy change in Eu-Ga-Ge clathrates

Abstract

A novel method has been developed to efficiently produce composites of Eu-Ga-Ge clathrates through the process of spark plasma sintering (SPS) under varying pressures, temperatures, and times. This technique enables the adjustment of the α and β phase ratios, thereby allowing for the fine-tuning of material properties. The resulting composite exhibits a cohesive growth of both phases rather than a mere mechanical mixture, making it suitable not only for enhancing magnetic applications but also for improving various other physical properties including thermoelectric characteristics. The article focuses on the investigation of magnetocaloric properties in composites with different phase ratios. Remarkably, it was observed that an appropriately balanced ratio between the two phases yields a distinct table-like curve depicting magnetic entropy change, consequently leading to a enhanced refrigeration capacity (RC). Additionally, a hybrid sample was obtained through the mechanical mixing of several Eu-Ga-Ge β phases with different Tc values. The hybrid also exhibits a magnetic entropy change curve with a table-like shape. A comparative analysis between these two methods was conducted.