“…16,17,53,54,88,[157][158][159] Beginning from a high quality nearstoichiometric crystal towards congruent composition, strong inhomogeneous broadening mechanisms are observed due to the intrinsic defects. 15,52 Thus, discrepancies can easily arise when comparing two different crystal stoichiometries. In this work, the A/c H parameter is used as a more suitable calibration factor due to the proportionality between the total OH − absorption band area and the hydrogen concentration.…”