Hydrogenation-induced changes of the crystal structure and magnetic properties of Er2Ni2Sn

Abstract Hydrogenation of the intermetallic compound Er 2 Ni 2 Sn (Mo 2 FeB 2 -type structure) was studied. The hydride Er 2 Ni 2 SnH 3.5 was formed under a hydrogen pressure of 65 kPa, after heating up to 373 K. The structure type of the metal sublattice was preserved, but the hydrogenation resulted in anisotropic lattice expansion prevailing in the crystallographic direction c . A lower hydride, Er 2 Ni 2 SnH 3.5- х , was obtained by heating Er 2 Ni 2 SnH 3.5 up to 573 K in dynamic vacuum. For Er 2 Ni 2 SnH 3.5- х the lattice expansion in the ab plane was accompanied by a reduction of the lattice parameter c . Er 2 Ni 2 Sn is an antiferromagnet with T N  = 6.1 K, whereas the hydrides Er 2 Ni 2 SnH 3.5 and Er 2 Ni 2 SnH 3.5- х remain paramagnetic down to 2 K (limit of the measurements). Hydrogenation results in weakening of the magnetic interactions, in agreement with the decrease of the conduction electron concentration caused by chemical bonding between hydrogen and metal atoms.