An investigation was made of H-induced defects in BaTiO3, PbTiO3, PbZrO3 and strontium bismuth tantalate. It was found that interstitial H produced a shallow level and OH– ions leading to a loss of switchable polarization if the oxide's band-gap was under about 4.2eV, but H was deep in wide gap compounds like BaZrO3. In strontium bismuth tantalate, H was more stable in the Bi–O layer.

Hydrogen-Induced Defects and Degradation in Oxide Ferro-Electrics. K.Xiong, J.Robertson: Applied Physics Letters, 2004, 85[13], 2577-9