Structure and Ferroelectric Properties of Modified Lead-Free Perovskite Materials

Politova, E.D.; Kaleva, G.M.; Mosunov, A.V.; Stefanovich, S.Y.; Sadovskaya, N.V.; Kiselev, D.A.; Ilina, T.I.; Shvartsman, V.V.

Авторы: Politova E.D., Kaleva G.M., Mosunov A.V., Stefanovich S.Y., Sadovskaya N.V., Kiselev D.A., Ilina T.I., Shvartsman V.V.
Сборник: Abstract book 12th INTERNATIONAL ADVANCES IN APPLIED PHYSICS & MATERIALS SCIENCE CONGRESS & EXHIBITION (APMAS 2022)
Тезисы
Год издания: 2022
Место издания: Turcica
Первая страница: 48
Последняя страница: 49
Аннотация: Lead-free perovskite materials are being intensively studied mainly in order to replace widely used Pb-based ones. They are promising for development of materials for capacitors, piezoelectrics, electrocaloric and other devices. We studied influence of cation substitutions and preparation conditions on structure parameters, microstructure, dielectric, relaxor ferroelectric, and piezoelectric properties of solid solutions in the systems based on (K0.5Na0.5)NbO3 (KNN), BaTiO3 (BT) and (Na0.5Bi0.5)TiO3 (NBT) perovskites. Ceramic samples in systems KNN-BT, NBT-BT with compositions close to Morphotropic Phase Boundaries (MPB) were prepared by the two-step solidstate reaction method at temperatures of 800 – 1450 K. The samples were additionally modified by acceptor and donor cations in A- and B-sites of perovskite lattice, and various overstoichiometric additives with low melting temperatures were used to improve density of ceramics. Ceramics were characterized using complex of physical-chemical methods: X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Second Harmonic Generation (SHG), Dielectric Spectroscopy (DS) and Atomic Force Microscopy in Piezorespone Force mode (PFM). The unit cell volume changes were observed by the XRD method in modified ceramics depending on ionic radii of substituting cations. Ferroelectric phase transitions at ~ 400 – 700 K were confirmed using the DS and SHG methods. At high temperatures > 800K effects of dielectric relaxation were observed in NBT-based ceramics studied caused by formation of oxygen vacancies in compositions with aliovalent substitutions. At the room temperature, non monotonous changes of the dielectric parameters and increase in the spontaneous polarization values were proved for modified ceramics. Using the PFM method ferroelectric polarization switching at nanoscale was proved, and increase of effective d33 piezoelectric coefficient in some modified KNN- and NBT-based ceramics correlated with increase in dielectric permittivity was observed. The results obtained confirmed improvement of functional properties and prospects of new lead-free piezoelectric and electrocaloric materials development on the base of modified KNN- and NBT-based compositions.
Добавил в систему: Мосунов Александр Викторович

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