Hydrogen-induced defects and degradation in oxide ferroelectrics

We investigate hydrogen-induced defects in BaTiO3, PbTiO3, PbZrO3, and strontium bismuth tantalate (SBT). We find that interstitial hydrogen produces a shallow level and OH− ions leading to loss of switchable polarization if the oxide’s band gap is under about 4.2eV, but hydrogen is deep in wide gap compounds like BaZrO3. In SBT, hydrogen is more stable in the Bi–O layer.