Local-electrostatics-induced oxygen octahedral distortion in perovskite oxides and insight into the structure of Ruddlesden-Popper phases.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 34545102.
- Also identified by DOI 10.1038/s41467-021-25889-6 and PMC identifier 8452630.
- Licence recorded as CC BY.
- The licence permits redistribution, so the abstract is shown in full and the full text is available from the publisher.
Abstract
As the physical properties of ABX<sub>3</sub> perovskite-based oxides strongly depend on the geometry of oxygen octahedra containing transition-metal cations, precise identification of the distortion, tilt, and rotation of the octahedra is an essential step toward understanding the structure-property correlation. Here we discover an important electrostatic origin responsible for remarkable Jahn-Teller-type tetragonal distortion of oxygen octahedra during atomic-level direct observation of two-dimensional [AX] interleaved shear faults in five different perovskite-type materials, SrTiO<sub>3</sub>, BaCeO<sub>3</sub>, LaCoO<sub>3</sub>, LaNiO<sub>3</sub>, and CsPbBr<sub>3</sub>. When the [AX] sublayer has a net charge, for example [LaO]<sup>+</sup> in LaCoO<sub>3</sub> and LaNiO<sub>3</sub>, substantial tetragonal elongation of oxygen octahedra at the fault plane is observed and this screens the strong repulsion between the consecutive [LaO]<sup>+</sup> layers. Moreover, our findings on the distortion induced by local charge are identified to be a general structural feature in lanthanide-based A<sub>n + 1</sub>B<sub>n</sub>X<sub>3n + 1</sub>-type Ruddlesden-Popper (RP) oxides with charged [LnO]<sup>+</sup> (Ln = La, Pr, Nd, Eu, and Gd) sublayers, among more than 80 RP oxides and halides with high symmetry. The present study thus demonstrates that the local uneven electrostatics is a crucial factor significantly affecting the crystal structure of complex oxides.