X-ray study of the ferroelectric [Ba0.6 Sr0.4] [(YTa)0.03 Ti0.94] O3

We have studied the system [Ba0.6 Sr0.4] [(YTa)0.03 Ti0.94] O3, as produced using two different sintering temperatures. It was shown by others that for a sample sintered at 1550°C the material is a relaxor, whereas for the same composition produced with sintering temperature of 1600°C the sample is a normal ferroelectric. We have employed analysis of x-ray diffraction peak broadening, Ti K edge x ray near edge spectroscopy, and extended x-ray absorption edge fine structure spectroscopy of Ta and Y sites in our study. We find that the 1550°C sinter sample has over double the lattice strain as does the 1600°C sample. For the lower temperature sinter material, both Ta and Y go to sites substitutional for Ti in the lattice, with a significant expansion (contraction) of the local perovskite structure about Y (Ta) dopants. Thus, with only three percent B site addition of Y and Ta dopants, there is a strain associated relaxor behavior produced in a bulk sample. For the higher temperature sinter specimen, there is a marked change in the average Y environment relative to the lower temperature sinter sample.