EXAFS study of lead-free relaxor ferroelectric Ba Ti1-x Zrx O3 at the Zr K edge

Abstract

Extended x-ray absorption fine structure experiments at the Zr K edge were carried out on perovskite relaxor ferroelectrics Ba Ti1-x Zrx O3 (BTZ) (x=0.25,0.30,0.35), and on BaZr O3 for comparison. Structural information up to 4.5 Å around the Zr atoms is obtained, revealing that the local structure differs notably from the average Pm 3̄ m cubic structure deduced from the 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 BaZr O3, 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 could be influenced by the random elastic fields generated by this particular chemical arrangement. © 2006 The American Physical Society.