The ordering of the Sc3+ and Ta5+ ions in Pb (Sc0.5Ta0.5) O3 can be varied by proper heat treatments (1000–1500°C). The ferroelectric → paraelectric transition is strongly influenced by this ordering. With decreasing order parameter Ω the phase transition becomes more diffuse and a number of properties show strong changes.
Stenger, C. G. F., Scholten, F. L., & Burggraaf, A. J. (1979). Ordering and diffuse phase transitions in Pb(Sc0.5Ta0.5)O3 ceramics. Solid state communications, 32(11), 989-992. https://doi.org/10.1016/0038-1098(79)90812-3