Determination of the Crystal Structures in the A-Site-Ordered YBaMn2O6 Perovskite

Blasco, J. ; Subias, G. ; Garcia-Muñoz, J.L. ; Fauth, F. ; Garcia, J.

Resumen: We present a complete structural study of the successive phase transitions observed in the YBaMn2O6 compound with the layered ordering of cations on the perovskite A-site. We have combined synchrotron radiation X-ray powder diffraction and symmetry-adapted mode analysis to describe the distorted structures as pseudosymmetric with respect to the parent tetragonal structure. The YBaMn2O6 compound shows three consecutive phase transitions on cooling from 603 K down to 100 K. It undergoes a first-order structural transition at T-1 approximate to 512 K from a C2/m cell with a single Mn site to a P2(1)/c cell with two nonequivalent Mn sites. No checkerboard ordering of the two types of MnO6 octahedra is revealed, and there is no significant charge segregation. A second transition is observed below T-2 approximate to 460 K giving rise to a duplication of the c-axis and the occurrence of four nonequivalent Mn sites. These sites are grouped in two pairs, producing, in this case, a checkerboard arrangement in the ab-plane with an average charge segregation of Delta q approximate to 0.4 e(-). The observed distortions in this phase disagree with the formation of an orbital-ordered phase. Finally, another structural transition is observed coupled to the magnetic transition at TN approximate to 200 K and the c-axis is no longer duplicated. The low-temperature phase is polar with SG P2(1). It also contains four nonequivalent Mn sites grouped in two pairs. The charge difference between these pairs is increased, achieving a value of Delta q approximate to 0.7 e(-). In this phase, an asymmetric stretching mode favors a Jahn-Teller-like distortion in the expanded MnO6 octahedra that could be associated with an ordering of eg (3d(x)(-z)(2)(2)/3d(y)(-z)(2)(2)) orbitals. Our refinements disclose that this phase is ferroelectric with significant polar displacements of the Mn and O-basal atoms along the b-axis. The simultaneous occurrence of ferroelectricity and magnetic ordering indicates that YBaMn2O6 can be considered as a type II multiferroic compound and can present magnetoelectric coupling.

Idioma: Inglés

DOI: 10.1021/acs.jpcc.1c04697

Año: 2021

Publicado en: JOURNAL OF PHYSICAL CHEMISTRY C 125, 35 (2021), 19467-19480
ISSN: 1932-7447

Factor impacto JCR: 4.177 (2021)

Categ. JCR: CHEMISTRY, PHYSICAL rank: 78 / 165 = 0.473 (2021) - Q2 - T2
Categ. JCR: MATERIALS SCIENCE, MULTIDISCIPLINARY rank: 143 / 345 = 0.414 (2021) - Q2 - T2
Categ. JCR: NANOSCIENCE & NANOTECHNOLOGY rank: 62 / 109 = 0.569 (2021) - Q3 - T2

Factor impacto CITESCORE: 7.0 - Energy (Q1) - Materials Science (Q1)

Factor impacto SCIMAGO: 1.103 - Electronic, Optical and Magnetic Materials (Q1) - Surfaces, Coatings and Films (Q1) - Physical and Theoretical Chemistry (Q1) - Energy (miscellaneous) (Q1)

Financiación: info:eu-repo/grantAgreement/ES/DGA/E12-20R
Financiación: info:eu-repo/grantAgreement/ES/MCIU/RTI2018-098537B-C21
Financiación: info:eu-repo/grantAgreement/ES/MCIU/RTI2018-098537B-C22
Financiación: info:eu-repo/grantAgreement/ES/MICIU/CEX2019-000917-S

Tipo y forma: Artículo (PostPrint)