Abstract
Specific-heat data (at zero field and 15.6 kV/cm), dielectric data, and electrocaloric data measured on a KTa crystal between 2 and 25 K are reported. The zero-field specific heat is about 30 times larger than the Debye prediction ( K) at these temperatures but shows no anomaly characteristic of a sharp phase transition as suggested by the neutron data. A very broad transition is possible around 10 K for which cal . From the specific-heat difference , a soft-mode frequency of 22.9 is determined near 10 K. The electrocaloric effect consists of reversible and irreversible components. The reversible effect is in good thermodynamic agreement with the specific-heat and dielectric data and with published data on the Gibbs free-energy coefficients. Both the irreversible effect and the dielectric data indicate that KTa does not retain a center of symmetry at low temperatures.
- Received 15 September 1976
DOI:https://doi.org/10.1103/PhysRevB.16.433
©1977 American Physical Society