Comparison of Structural Properties of a Pb-free relaxor to PMN

The Pb-free perovskite, BaZn$_{0.317}$Nb$_{0.633}$Ti$_{0.05}$O$_3$, has been reported to be a ferroelectric relaxor with a permittivity that has a stronger frequency shift than Pb-based relaxors [1]. We report neutron powder diffraction measurements which were performed over a 450 K temperature range on this compound. The results are compared to PMN, and it is shown that the atomic displacements and the thermal expansion of these two compounds are very dissimilar. [1] L. Khemakhem et al., J. Alloys Compd. 452, 451 (2008).