The chemical and physical nature of the hydride ion is briefly treated. Sev
eral reactions of the hydride ion in oxides or oxygen atmosphere are given,
A number of perovskites and inverse perovskites are listed. which contain
the H- ion on the oxygen or B-anion sites in the archetype ABO(3) System. H
- is stable with respect to oxide and halide anions but, among cations only
with respect to oxides and halides of strongly electropositive metals such
as alkaline, alkaline-earth and main group III metals. H- is only stable i
n combination with transition metal ions of certain elements in their lowes
t positive oxidation state. Mixed oxide/hydride containing perovskites may
thus exist. Steinsvik et al. have recently suggested a defect model for a p
erovskite including substitutional hydride ions on the oxygen site, H-O(.),
and protons associated with a lattice oxygen, OHO.. The defect equations f
or this acceptor doped A(II)B(IV)O-3 model compound are solved without usin
g the conventional Brouwer approximations, One case is presented where hydr
ide formation is suppressed, and another case where it is promoted. Plots o
f concentration versus water and oxygen partial pressures show new interest
ing features these are discussed. (C) 2001 Elsevier Science B.V. All rights
reserved.