The Influence of Hydrogenation on the Structure, Magnetic and Magnetocaloric Properties of Tb–Dy–Co Alloys with a Laves Phase Structure

Abstract

A complex study of structure, phase composition, surface topology, magnetic, and magnetocaloric properties was performed for TbCo₂ and Tb_0.3Dy_0.7Co₂ compounds and for a Tb_0.3Dy_0.7Co₂H_0.5 hydride with a low hydrogen content. The hydrogenation was established to impact the structural features at the micro- and nanolevels, as well as the fundamental and functional properties. Introducing even a small amount of hydrogen in the crystal lattice of Tb_0.3Dy_0.7Co₂ compound is found to cause an increase in both the Curie temperature and the magnetic moment at the cobalt atoms. The magnetic phase transition from the paramagnetic to the magnetically ordered state changes from the first (in Tb_0.3Dy_0.7Co₂) to the second (in TbCo₂ and Tb_0.3Dy_0.7Co₂H_0.5) order, leading to a noticeable decrease in the magnetocaloric effect.