Phase stability and structural transitions in compositionally complex LnMO(3) perovskites

0543953 - ÚJF 2022 RIV US eng J - Journal Article
Cedervall, J. - Clulow, R. - Bostrom, H. L. B. - Joshi, D. C. - Andersson, M. S. - Mathieu, R. - Beran, Přemysl - Smith, R.I. - Tseng, J. - Sahlberg, M. - Berastegui, P. - Shafeie, S.
Phase stability and structural transitions in compositionally complex LnMO(3) perovskites.
Journal of Solid State Chemistry. Roč. 300, AUG (2021), č. článku 122213. ISSN 0022-4596. E-ISSN 1095-726X
R&D Projects: GA MŠMT LM2015056
Research Infrastructure: CANAM II - 90056; Reactors LVR-15 and LR-0 II - 90120
Institutional support: RVO:61389005
Keywords : Perovskites * phase transitions * high entropy oxides * magnetism
OECD category: Condensed matter physics (including formerly solid state physics, supercond.)
Impact factor: 3.656, year: 2021
Method of publishing: Open access
https://doi.org/10.1016/j.jssc.2021.122213

Entropy stabilised materials have possibilities for tailoring functionalities to overcome challenges in materials science. The concept of configurational entropy can also be applied to metal oxides, but it is unclear whether these could be considered as solid solutions in the case of perovskite-structured oxides and if the configurational entropy plays a stabilising role. In this study, compositionally complex perovskite oxides, LnMO(3) (Ln = La, Nd, Sm, Ca and Sr, M = Ti, Cr, Mn, Fe, Co, Ni, and Cu), are investigated for their phase stability and magnetic behaviour. Phase-pure samples were synthesised, and the room temperature structures were found to crystallise in either Pnma or R (3) over barc space groups, depending on the composition and the resulting tolerance factor, while the structural transition temperatures correlate with the pseudo cubic unit cell volume. The techniques used included diffraction with X-rays and neutrons, both ex- and in-situ, X-ray photoelectron spectroscopy, magnetometry as well as electron microscopy. Neutron diffraction studies on one sample reveal that no oxygen vacancies are found in the structure and that the magnetic properties are ferrimagnetic-like with magnetic moments mainly coupled antiferromagnetically along the crystallographic c-direction. X-ray photoelectron spectroscopy gave indications of the oxidation states of the constituting ions where several mixed oxidation states are observed in these valence-compensated perovskites.
Permanent Link: http://hdl.handle.net/11104/0321042