Changes induced by annealing in the low temperature properties of linbo3

Abstract Measurements of the heat capacity of LiNbO3 single crystal subjected to different thermal treatments are presented. We correlate its observed behaviour with the amount of hydroxyl ions determined by means of optical absorption. We conclude that the OH− ions contribute to the heat capacity in two ways: through a linear term, as observed in glasses and in some ferroelectrics, and, in the lower temperature range of our experiments, through an additional contribution that can be well fitted by a Schotky curve.