Nano-sized polar clusters with tetragonal symmetry in PbTiO3-based relaxor ferroelectrics

The behavior of nanometer-sized polar clusters is considered to be of central importance to the understanding of relaxor ferroelectricity. The size of the polar clusters with tetragonal symmetry in PbTiO3-based relaxors was estimated by analyzing the degree of asymmetric Raman line broadening. It was shown that the mean size (L) of the tetragonal polar clusters remained essentially constant with L approximately 1.2 nm for temperatures above 300 K. The estimated L increases rapidly below a certain critical temperature, suggesting a rapid growth of the frozen polar clusters with the same tetragonal symmetry.