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Correlative chemical and structural nanocharacterization of a pseudo‐binary 0.75Bi(Fe 0.97 Ti 0.03 )O 3 ‐0.25BaTiO 3 ceramic
Author(s) -
McCartan Shane J.,
Calisir Ilkan,
Paterson Gary W.,
Webster Robert W. H.,
Macgregor Thomas A.,
Hall David A.,
MacLaren Ian
Publication year - 2021
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.17599
Subject(s) - materials science , octahedron , ceramic , inner core , electron energy loss spectroscopy , annealing (glass) , microstructure , ferroelectricity , nanostructure , ternary operation , electron diffraction , aurivillius , crystal structure , crystallography , diffraction , nanotechnology , dielectric , chemistry , optics , transmission electron microscopy , composite material , physics , optoelectronics , computer science , programming language
Fast cooling after sintering or annealing of BiFeO 3 ‐BaTiO 3 mixed‐oxide ceramics yields core‐shell structures that give excellent functional properties, but their precise phase assemblage and nanostructure remains an open question. By comparing conventional electron energy loss spectroscopy (EELS) with scanning precession electron diffraction (SPED) mapping using a direct electron detector, we correlate chemical composition with the presence or absence of octahedral tilting and with changes in lattice parameters. This reveals that some grains have a three‐phase assemblage of a BaTiO 3 ‐rich pseudocubic shell; a BiFeO 3 ‐rich outer core with octahedral tilting consistent with an R3c structure; and an inner core richer in Ba and even poorer in Ti, which seems to show a pseudocubic structure of slightly smaller lattice parameter than the shell region. This last structure has not been previously identified in these materials, but the composition and structure fit with previous studies. These inner cores are likely to be non‐polar and play no part in the ferroelectric properties. Nevertheless, the combination of EELS and SPED clearly provides a novel way to examine heterogeneous microstructures with high spatial resolution, thus revealing the presence of phases that may be too subtle to detect with more conventional techniques.