High-resolution X-ray diffraction is applied to investigate macro and micro crystal structure changes across different synthesis routes in BNBT4 piezoceramics. Synthetic powders were obtained by conventional sol-gel auto combustion and mixed oxides methods; then samples were sintered by combining hot uniaxial pressing and subsequent recrystallization. The crystal structure of the ceramic obtained by sol-gel is rhombohedral (R3c) and the one obtained from mixed oxides is monoclinic (Cc). In the sol-gel case, a poling process produces an intense 001 texture parallel to the polarizing electric field. Poling the mixed oxides ceramics quickly transforms the structure from monoclinic to rhombohedral while texture and anisotropic micro-strains develop further as the poling increases. A correlation between detected structural transformations and variations in selected physical properties is suggested. The anisotropy of the critical temperatures for dielectric and electromechanical depolarization is lower for mixed oxides ceramics than for sol-gel ceramics. © 2022 Elsevier Inc.

Dr. Carmen Galassi (INSTEC, Faenza) is greatly acknowledged for providing synthetic sol-gel and mixed oxides powders. Mr. Alvaro García (ICMM) and Mr. Nico Baumbach (Ilmenau Tech. University and short stay at ICMM under RISE - Program (Research Internships in Science and Engineering). DAAD - German Academic Exchange Service) are acknowledged for the assistance with the thermal depolarization measurements. This work was partially funded by the Spanish project MAT2017_86168-R. The support provided by CONACYT, Mexico, Projects No. 183706 and C-614/2021, is acknowledged. X-ray diffraction measurements were performed in Elettra Sincrotrone Trieste as part of Proposals No. 20180277 and 20215805. The authors express their gratitude to International Centre for Theoretical Physics the ample research support.

Peer reviewed