Electron diffraction of tilted perovskites

Abstract

Simulations of electron diffraction patterns for each of the known perovskite tilt systems have been performed. The conditions for the appearance of superlattice reflections arising from rotations of the octahedra are modified to take into account the effects of different tilt systems for kinematical diffraction. The use of selected-area electron diffraction as a tool for perovskite structure determination is reviewed and examples are included.

The influence of Mn substitution on the local structure of Na0.5Bi0.5TiO3 crystals: Increased ferroelectric ordering and coexisting octahedral tilts

“…5(a). This type of in-phase octahedral tilt system generally occurs in tetragonal structures, 64,69 whereas rhombohedral (R3c) structures of perovskite often have an anti-phase 1/2 (ooo) octahedral tilting about the pseudocubic axes. 64 In Figs.…”

“…It has been noted that these superlattice reflections originate from slight deviations from the ideal perovskite structure, which could have intensity contributions from: (i) oxygen octahedral tilts; (ii) chemical ordering of the A-site cations; and/or (iii) antiparallel displacements of cations. 21,[64][65][66][67][68][69] In NBT, following theoretical 21 and experimental studies, 68,69 it is believed that oxygen octahedral tilting is the dominate source of the intensity. 32,70 Evidence of in-phase octahedral tilting in Mn-NBT at room temperature was apparent in (001) SAED patterns by weak 1/2 (ooe) superlattice reflections, as marked by an arrow in Fig.…”

Observation of partially incoherent ⟨110⟩ boundaries between polar nanodomains in Na1/2Bi1/2TiO3 single crystals

“…These superlattice reflections could have intensity contributions from ͑i͒ oxygen octahedral tilts; ͑ii͒ chemical ordering of the A-site cations; and/or ͑iii͒ antiparallel displacements of cations. 14,18,19,21,[23][24][25] In fact, recent investigations 18,21 have provide evidence that these superlattice reflections arise due to M-type oxygen octahedral rotations, typical of rotated T or O structures; rather than the R-type typical of a R one. Our observations, in the inset of Fig.…”

Microstructural origin for the piezoelectricity evolution in (K0.5Na0.5)NbO3-based lead-free ceramics

“…The ceramic specimens were poled at a series of electric fields at room temperature (25 C) for 10 min. The piezoelectric coefficient d 33 was measured with a piezo-d 33 meter (ZJ-4B, Institute of Acoustics, Chinese Academy of Sciences) 24 h after poling. For dielectric properties measurements, silver paste (Dupont 6160) was fired on at 750 C for 6 min as electrodes.…”