Temperature evolution of short- and medium-range ionic correlations in relaxor ferroelectric [Pb(Zn1/3Nb2/3)O3]1-x[PbTiO3]x (x=0.05, 0.12)

We performed temperature-dependent neutron pair distribution function (PDF) analysis on relaxor ferroelectric [Pb(Zn1/3Nb2/3)O-3](1-x)[PbTiO3](x) (PZN-xPT) (x=0.05 and 0.12) from 550 to 150 K. The experimental PDF spectra clearly demonstrate that PZN-5%PT and PZN-12%PT have basically same ionic pair correlations up to the pair distance r similar to 15 A at all temperatures despite their difference in low-temperature long-range crystal structures. At longer pair distances 30 < r < 50 A, however, ionic pair correlations of PZN-5%PT and PZN-12%PT gradually diverge from each other below T similar to 450 K. Based on these PDF results, we propose that a distinct ordering of polar nanoregions develops between PZN-5%PT and PZN-12%PT with decreasing temperature.