Phase transition sequence in sodium bismuth titanate observed using high-resolution x-ray diffraction

High resolution powder x-ray diffraction patterns of Na 0.5 Bi 0.5 TiO 3 at selected temperatures were examined to compare structural changes with observed piezoelectric thermal depoling temperatures. The depoling temperatures do not correlate with discrete phase transition temperatures, and therefore, a structural transition is not the origin of thermal depoling. Rather, a correlation is made with an increase in volume fraction of material which does not obey the long-range Cc space group. The origin of the thermal depoling behavior may be the loss of long-range ferroelectric order by a decreasing proportion of the Cc phase or the associated percolation of disordered nano-scale platelets.