Dielectric dispersion and Raman spectroscopy in PbHfO3 single crystals modified by addition of Sn ions

Dielectric studies of a PbHf1-xSnxO3 (with x = 0.025) single crystal undergoing two structural phase transformations at about 426 and 474 K were performed in broad frequency and temperature ranges. Phase transitions sequence and their nature were established on the basis of differential scanning calorimetry measurements. Investigations of the complex dielectric permittivity in the frequency range 20 Hz to 2 MHz revealed dipolar dielectric dispersion that exists before AFE2-PE phase transition and is connected with the motion of domain walls. Analysis of temperature evolution of the first-order Raman light scattering spectra confirmed the sequence of phase transitions and gave evidence of locally broken cubic symmetry in the sample due to polar clusters of lower symmetry.