Abstract
Hydrogen interaction with intermetallic compound Nd2Ni2Mg crystallizing in the tetragonal Mo2FeB2 type of structure leads to the formation of hydride/deuteride containing 7.4-8 H(D)/f.u. Hydrogen absorption is accompanied by a monoclinic deformation of the unit cell with the crystal structure data refined from Synchrotron XRD (Sp. gr.
P2(1)/c; a = 11.60733(5) angstrom; b = 7.66057(3) angstrom; c = 11.78743(5) angstrom, beta = 92.4126(4)degrees, V = 1047.194(8) angstrom(3)) and high resolution powder XRD data. The formed interstitial hydride disproportionates during heating forming NdH2.
Nd2Ni2Mg is an antiferromagnet with the Neel temperature T-N approximate to 19 K. Presence of another magnetic phase transition at 14 K together with two metamagnetic transitions indicates a complicated magnetic phase diagram.
The hydrogenation reduces T-N to 1.0 K.