Rhombohedral R3c to orthorhombic Pnma phase transition induced by Y-doping in BiFeO3

GRAF, M.E.; DI NAPOLI, S.; BARRAL, M.A.; SALEH MEDINA, L.M.; NEGRI, R.M.; SEPLIARSKY, M.; LLOIS, A.M.

JOURNAL OF PHYSICS CONDENSED MATTER

IOP PUBLISHING LTD

Lugar: Londres; Año: 2018 vol. 18 p. 285701 - 285704

0953-8984

In this work we study, by means of ab initio calculations, the structural, electronic andmagnetic properties of Y-doped BiFeO3 compounds. We determine that there is a morphotropicphase boundary at an yttrium concentration of (18 ± 2)%, where the structure changes from R3c to Pnma. This structural transition is driven by the chemical pressure induced by the dopant.By analyzing the evolution of the oxygen octahedral tilts we find an enhancedantiferrodistortive distortion when increasing the Y-doping, together with a reduction of the ferroelectric distorsion, that gives rise to a smaller value of the electric polarization. These cooperative effects should lead to a larger canting of the Fe magnetic moments and to a larger ferromagnetic response in the R3c phase, as it is observed in the experiments.Keywords: BiFeO3, Y doping, phase transition, ab initio calculations