Photoacoustic phase transition of the ceramic BaTiO3

Photoacoustic signals from the ceramic BaTiO3 are analyzed, as a function o f temperature close to structural phase transition from tetragonal to cubic at 110 degrees C. The amplitude of the signals depends on the changes of t he thermoelastic properties in the ceramic with temperature. The Curie temp erature value for the phase change was reproducible and was found to be 109 +/-6 degrees C. A comparative analysis of this result with the differential thermal analysis and permittivity techniques is performed. Two changes of sign in the photoacoustic signal are observed, associated with the thermal expansion coefficient behavior in this material near the transition. (C) 19 98 American Institute of Physics. [S0003-6951(98)04431-3].