Materials and Nanoscience, Nebraska Center for (NCMN)


Date of this Version



Published in Journal of Physics: Condensed Matter 20 (2008), 285214 (5pp); doi:10.1088/0953-8984/20/28/285214 1 Copyright © 2008 IOP Publishing Ltd. Used by permission. Online at


A 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 in a very low-temperature range, 0.6–1.5 K, and moderately low-temperature range, 1.5–5 K, in addition to the expected Debye terms, we observed significant contributions originating from the linear and Einstein terms, which we attributed as the manifestation of low-lying elementary excitations due to lattice vibrations occurring 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 behavior in both low and high frequency regions.