Unveiling the strain and structural ferroelectric phase transition induced by temperature in lead titanate perovskite modified with 40% of calcium

Structurally correlated ferroelectric phase transitions induced by temperature are reported for the solid solution Pb0.6Ca0.4TiO3 compound. Such phase transitions were analyzed by considering different parameters, such as lattice parameters, microstrain, dielectric properties, and thermal analysis. Synchrotron x-ray diffraction and Rietveld refinement studies revealed a tetragonal symmetry from room temperature up to ∼550 K and uniaxial microstrain from room temperature to ∼400 K. The first thermally driven phase transition observed was from displacive ferroelectric tetragonal symmetry to another non-displacive tetragonal symmetry. The next phase transition was from the tetragonal to cubic. The electric permittivity as a function of temperature for frequency from 1 kHz to 1 MHz and the differential scanning calorimetry report features typical of ferroelectric–paraelectric phase transition only around 400 K, and no other abrupt change in properties is observed at 550 K, indicating the sequence of first- and then second-order phase transition.