EXAFS study of lead-free relaxor ferroelectric BaTi1-xZrxO3 at the ZrK edge

Extended x-ray absorption fine structure experiments at the Zr K edge were carried out on perovskite relaxor ferroelectrics BaTi1-xZrxO3 (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 Pm3m 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 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 could be influenced by the random elastic fields generated by this particular chemical arrangement. (c) 2006 American Institute of Physics.