Lead-based relaxor ferroelectrics by Raman scattering

Title: Lead-based relaxor ferroelectrics by Raman scattering Author: Iegor Rafalovskyi Institute: Institute of Physics of the Czech Academy of Sciences Supervisor: Ing. Jiří Hlinka, Ph.D., Department of Dielectrics, Institute of Physics of the Czech Academy of Sciences Abstract: The following work is dedicated to measurement and analysis of Raman scat- tering spectra of different perovskite ferroelectrics, mainly lead-based relaxors in the form of bulk and thin films. Investigation of single crystal MPB composition PMN-0.32PT has shown that procedure of zero-field heating of previously field-cooled sample leads to sta- bilization of heterophase pattern with 10-100 µm parallel stripes of alternating tetragonal and rhombohedral (rhombohedral-like) phases. Another point of interest investigated in PMN-0.32PT is rhombohedral to tetragonal phase transition induced by electric field. The domain structure with 90-degree domain walls has been observed in relaxor based composition PFN-0.38PT. Adjacent domains were investigated by polarized Raman scat- tering to confirm their structure and symmetry. Relaxor ferroelectric PSN has shown totally different behavior in polarized Raman spectra if studied in the form of single crystal or epitaxial thin film. The normalized cross-polarized intensity of 810 cm−1 band measured in..