Multifunctional phenomena in Tb-Dy-Gd(Ho)-Co(Al) compounds with a Laves phase structure: Magnetostriction and magnetocaloric effect

This paper presents a review and results of a comparative study of the magnetocaloric and magnetostriction properties for the four multicomponent systems TbxDyyGdzCo2, TbxDyyHozCo2, TbxDyyGdz(-Co,Al)(2) and TbxDyyHoz(Co,Al)(2) (x + y + z = 1). All compounds have a Laves-phase MgCu2-type structure at room temperature. A magneto-structural phase diagram is constructed for the compounds under study. We showed that the Curie temperatures (T-C), the values of magnetocaloric effect (MCE) and volume or anisotropic magnetostriction can be tuned by variation of element concentration in the rareearth and cobalt sublattices. When lattice parameter a increases from similar to 0.718 to 0.722 nm for Al-free compositions, the Curie temperature grows (from similar to 100 to 300 K), respectively. Partial substitution of Co by Al in the studied compounds also leads to an increase in Curie temperature. An important feature of multicomponent RCo2-type compounds (unlike pseudo-binary systems, e.g. (Tb,Dy)Co-2) is a weak MCE and volume magnetostriction dependence on the composition both within each of the systems and between the groups (TbxDyyGdzCo2 and TbxDyyGdz(Co,Al)(2)) when the Curie temperatures of the samples TC > 170 K. Regular recurrence and/or change of the magnetic properties across the varied composition of the compounds allows us to find materials with desired magnetic characteristics such as TC, MCE, and magnetostriction, to use them in practice. (C) 2020 Elsevier B.V. All rights reserved.