Random local strain effects in homovalent-substituted relaxor ferroelectrics: a first-principles study of BaTi0.74Zr0.26O3

Claire Laulhé (1) , Alain Pasturel (2) , Francoise Hippert (3) , Jens Kreisel (3)

1 SSOLEIL - Synchrotron SOLEIL
2 SIMaP - Science et Ingénierie des Matériaux et Procédés
3 LMGP - Laboratoire des matériaux et du génie physique

We present first-principles supercell calculations on BaTi0.74Zr0.26O3, a prototype material for relaxors with a homovalent substitution. From a statistical analysis of relaxed structures, we give evidence for four types of Ti-atom polar displacements: along the < 1 1 1 >, < 1 1 0 >, or < 1 0 0 > directions of the cubic unit cell, or almost cancelled. The type of a Ti displacement is entirely determined by the Ti/Zr distribution in the adjacent unit cells. The underlying mechanism involves local strain effects that ensue from the difference in size between the Ti4+ and Zr4+ cations. These results shed light on the structural mechanisms that lead to disordered Ti displacements in BaTi(1-x)Zr(x)O3 relaxors, and probably in other BaTiO3-based relaxors with homovalent substitution.

Mots clés: Relaxor ferroelectrics; ab-initio calculations; strain effects in ferroelectrics; perovskites

Domaines: Science des matériaux [cond-mat.mtrl-sci]

Claire Laulhé, Alain Pasturel, Francoise Hippert, Jens Kreisel. Random local strain effects in homovalent-substituted relaxor ferroelectrics: a first-principles study of BaTi0.74Zr0.26O3. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2010, 82, pp.132102. ⟨10.1103/PhysRevB.82.132102⟩. ⟨hal-00490197⟩