POLARIZED RAMAN-SPECTRA OF SINGLE-CRYSTALS OF BACEO3

Crystals of BaCeO3 were obtained by the zone melting technique using a n induction heating system, The crystals were studied by Raman spectro scopy at 10-983 K. They were found to be completely free from ceria, i n contrast to the compounds obtained previously by the usual powder me thod, Single crystals (typically of 20 mu m(3)) were identified and pr operly oriented under the microscope in order to give the largest Rama n intensity contrasts when varying the polarization of the incident an d scattered light. Five types of polarized spectra were obtained, The polarization data allowed the identification of 18 distinct bands amon g the 24 expected Raman-active modes of the low-temperature orthorhomb ic phase, These bands were tentatively assigned in terms of symmetry. A progressive gain of polarization of the bands was observed when a pr operly oriented crystal was submitted to thermal cycles between 25 and 600 degrees C. (C) 1997 by John Wiley & Sons, Ltd,