Further studies of the T3/2 specific heat term in ferroelectrics at low temperatures

Publisher Website
Google Scholar
Abstract
Measurements of a T3/2 contribution to the low-temperature specific heat of BaTiO3 and SrTiO3 ceramics and single-crystal TiO2 (rutile) are reported. The electric-field dependence of the T3/2 effect in BaTiO3 and SrTiO3 was studied. This unusual effect had previously been measured in unpoled single crystals of BaTiO3, LiNbO3, TGS, and KDP and in a PLZT 11/65/35 ceramic. The composite data on all these materials rule out explanations based on domain walls or twin boundaries or intergranular phenomena. A surface layer contribution is suggested by the data, and it is shown that such an explanation requires an ω ∞ q4/3 dispersion relation.