Specific heat study and Landau analysis of the phase transition inPbTiO3 single crystals

Abstract

The specific heat of pure lead titanate(PbTiO3) crystals grown by the float-zone method is reported at temperatures of 325–1250 K. Theexcess specific heat associated with the ferroelectric phase transition was analysed using a2–4–6 Landau potential to self-consistently determine the Curie–Weiss temperature, the transition points, the total transition enthalpy, as well as the latent heat and entropydiscontinuity at the first-order phase change. The temperature ranges over which variousexcess thermodynamic quantities obeyed the mean-field predictions of the Landau theorywere investigated. The coefficients of the Landau potential were also determined, and theresults compared to corresponding measurements made on pure polycrystalline leadtitanate specimens. The implications of the results with respect to prior discrepanciesreported for the first-order character of the phase transition in lead titanate crystals arediscussed.