Band Structures of Zirconium Hydrides

The band structures of zirconium hydride compounds are calculated using the APW method. By comparing the bands for a hypothetical f.c.c. compound ZrH 0 with f.c.c. ZrH 2 (corresponding to the Δ‐phase), it is shown that the hydrogen atoms give rise to a new ‘bonding’ band below the Fermi level. The band structures of two interstitial hydrogen h.c.p. compounds ZrH 0.5 and ZrH (α‐phase) are also calculated. For ZrH 0.5 with two Zr atoms and one H atom in the primitive unit cell no new bands are formed. For ZrH with two Zr atoms and two H atoms in the primitive unit cell a new band is formed just below the Fermi level but the band structure is similar to that of ZrH 0.5 and a‐Zr with the Fermi level raised. Estimates of the total energies show that the band structure contributions favour formation of f.c.c. ZrH 2 (corresponding to the Δ‐phase) over an interstitial α‐phase, as is observed experimentally.