EXAFS study of lead-free relaxor ferroelectric BaTi(1-x)Zr(x)O3 at the Zr K-edge

Claire Laulhé (1) , Francoise Hippert (1) , Jens Kreisel (1) , Mario Maglione (2) , Annie Simon (2) , Jean-Louis Hazeman (3) , Vivian Nassif (4)

1 LMGP - Laboratoire des matériaux et du génie physique
2 ICMCB - Institut de Chimie de la Matière Condensée de Bordeaux
3 Laboratoire de Cristallographie
4 SP2M - UMR 9002 - Service de Physique des Matériaux et Microstructures

Extended X-ray absorption fine structure (EXAFS) experiments at the Zr K-edge were carried out on perovskite relaxor ferroelectrics BaTi(1-x)Zr(x)O3 (BTZ) (x = 0.25, 0.30, 0.35), and on BaZrO3 for comparison. Structural information up to 4.5 A around the Zr atoms is obtained, revealing that the local structure differs notably from the average Pm-3m cubic structure deduced from X-ray diffraction. In particular, our results show that the distance between Zr atoms and their first oxygen neighbors is independent of the Zr substitution rate x and equal to that measured in BaZrO3, while the X-ray cubic cell parameter increases linearly with x. Furthermore, we show that the Zr atoms tend to segregate in Zr-rich regions. We propose that the relaxor behavior in BTZ is linked to random elastic fields generated by this particular chemical arrangement, rather than to random electric fields as is the case in most relaxors.

Mots clés: X-ray absorption spectroscopy; EXAFS; Barium zirconate titanate; BZT; Ferroelectricity and antiferroelectricity; Niobates; titanates; tantalates; PZT ceramics

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

Claire Laulhé, Francoise Hippert, Jens Kreisel, Mario Maglione, Annie Simon, et al.. EXAFS study of lead-free relaxor ferroelectric BaTi(1-x)Zr(x)O3 at the Zr K-edge. Physical Review B: Condensed Matter and Materials Physics (1998-2015), 2006, 74 (1), pp.014106. ⟨10.1103/PhysRevB.74.014106⟩. ⟨hal-00021474⟩