Investigations of the OH− absorption bands in congruent and near-stoichiometric LiNbO3:Hf crystalsWenbo Yan, Lihong Shi, Hongjian Chen, Xunan Shen and Yongfa KongEPL, 91 3 (2010) 36002DOI: https://doi.org/10.1209/0295-5075/91/36002