Hydrogen induced structural and magnetic transformations in magnetic regenerator materials ErNi n ( n=1, 2) and HoCu 2

Abstract

The effect of hydrogenation on the structures and magnetic properties of magnetic regenerators HoCu 2 (CeCu 2-type), ErNi 2 (MgCu 2-type) and ErNi (FeB-type) has been investigated. All these compounds can form crystalline hydrides which remain in the structure of the original compound. In the case of ErNi 2, hydrogenation induces volume expansion up to 13% compared with the parent compound. The magnetic moment and the Curie temperature of the crystalline hydrides decreases as the hydrogen content increases. In the case of ErNi and HoCu 2, there is a little change in the lattice parameters and magnetic properties of the crystalline hydrides compared with original compounds. Amorphous hydrides are also observed after the hydrogenation of ErNi 2 and HoCu 2 compounds.