Low-temperature specific-heat study has been performed on the insulating giant dielectric constant material CaCu3Ti4O12 and two related compounds, Bi2/3Cu3Ti4O12 and La0.5Na0.5Cu3Ti4O12, from 0.6 to 10 K. From analyzing the specific heat data at very low-temperature range, 0.6 to 1.5 K, and moderately low-temperature range, 1.5 to 5 K, in addition to the expected Debye terms, we noticed significant contributions originated from the linear and Einstein terms, which we attributed as the manifestation of low-lying elementary excitations due to lattice vibrations occurred at the grain boundaries and induced by local defects. Together with the findings on electronic and mechanical properties, a phenomenological model is proposed to explain the high dielectric constant behaviors at both low and high frequency regions.
@article{arxiv.0712.0129,
title = {A Low-Temperature Specific Heat Study of the Giant Dielectric Constant Materials},
author = {C. P. Sun and Jianjun Liu and J. -Y. Lin and Chun-gang Duan and W. N. Mei and H. D. Yang},
journal= {arXiv preprint arXiv:0712.0129},
year = {2009}
}