Oxygen nonstoichiometry and hydrogen bonds in BaTiO3

The origin of hydroxyl in the lattice of barium titanate as a consequence of the reaction of hydrogen with oxygen ions in the lattice is described. A band at the wave number 1770 cm^?1 was assigned to this hydroxyl in the infra-red spectrum. The samples were annealed in a stream of hydrogen and in sealed ampoules containing hydrogen or deuterium at temperatures above 900°C, and at 50 to 500° C when hydrogen plasma was used. The defect structure of the sample after prolonged annealing in hydrogen is discussed.