Raman study of temperature-induced phase transitions in lead hafnate (PbHfO₃)

Abstract

Results of a high-temperature Raman spectroscopic investigation up to 522 K carried out at ambient pressure on an antiferroelectric PbHfO₃ multi-domain single crystal are reported. The changes in the Raman spectral features show that temperature-induced phase transitions occur at 435 ± 1 and at 484 ± 1 K. The first transition is possibly to a tetragonal structure and the second is to the cubic perovskite phase. The behavior is consistent with the earlier x-ray study of PbHfO₃. No soft mode behavior associated with the transitions was detected in the Raman spectra of PbHfO₃. The changes observed in the high-temperature Raman spectra of PbHfO₃ are similar to those found in the spectra of isostructural PbZrO₃.