The crystal and electronic structure of CaPd3H

A new calcium substituted palladium hydride, CaPd3H, has been synthesized and the metal structure was found to be of the Ni3Ti (D024) type. From a Guinier-Hنgg X-ray powder diffraction pattern the unit cell dimensions were determined to be a = 5.8617(2) and c = 9.7793(6) إ. Resistance measurements did not reveal any superconducting transition, but the alloy has metallic character. From considerations of bonding distances in the binary hydrides, the hydrogen atoms are restricted to the octahedral site coordinated by six palladium atoms. The experimental results were confirmed by theoretical calculations on the electronic structure, using the LMTO method. The d-electron bands are filled at the CaPd3H composition, thus limiting the hydrogen occupancy to only one H atom per formula unit.