RAMAN-SPECTROSCOPY OF ORDERED AND DISORDERED PBIN1/2NB1/2O3 SINGLE-CRYSTALS

Raman scattering measurements were carried out for the ordered and disordered states of PbIn1/2 Nb1/2O3 (PIN) single crystals in the temperature range from 10 K to 1050 K. Sensitivity of the Raman method to the degree of order in the B site cations was confirmed. Sharp changes in the Raman spectra near the phase transition from the antiferroelectric to the paraelectric state (440 K) were detected for the ordered sample. Diffuse changes in the vicinity of the ferroelectric-paraelectric transition were seen in the disordered one. In the paraelectric phase, Raman lines of first order character have been found in the low-frequency range. The disappearance of these lines at higher temperature (1000 K) is discussed from the standpoint of a supplementary structural phase transition.