Evidence of presence of tweed in PbSc_0.5Ta_0.5O₃ crystals based on acoustic emission frequency spectrum analysis

Ferroelectric PbSc_0.5Ta_0.5O₃ crystals with high degree of chemical B-site order and relaxor PbSc_0.5Ta_0.5O₃ crystals with low degree of chemical B-site order were studied by acoustic emission near their intermediate characteristic temperature . The acoustic emission data were subjected to fast Fourier transform procedure. It was established that, while the acoustic emission spectrum amplitude of ordered PbSc_0.5Ta_0.5O₃ exhibits a gradual monotonic decrease as frequency decreases, the one of disordered PbSc_0.5Ta_0.5O₃ exhibits the additional features. The differences between the acoustic emission spectra are discussed in view of corresponding differences between polar nanoregions, characteristic for relaxors, and polar tweed pattern, characteristic for ferroelectrics.