IMF2017

The study of the phase transitions in the antiferroelectric crystals has been a challenging task for several years because of the presence of competing interactions between ferroelectricity and antiferroelectricity at phase transition point. In ferroelectric crystals phase transition at T_C is usually considered to be the result of softening of a single soft optic mode at the center of the Brillouin zone and/or relaxational processes which can exist in a given material. In the case of antiferroelectrics the situation is more complicated since the unstable mode is not in the center of the Brillouin zone. Typical example of an antiferroelectric crystal is PbZrO₃ (PZO). However, the nature of PZO’s transition is far from being settled, as new experimental results and conflicting physical pictures have recently been reported. Numerous Raman and Brilloiun scattering measurement of pure and doped PZO (inter alia PbZr_1-xSn_xO₃) crystals has not solved the problem of the existence of a classical soft mode although some promising experimental results was reported. Among the other experimental techniques that are able to measure "local" properties of the ferroelectrics and antiferroelectric phase transitions, Mössbauer spectroscopy seems to be forgotten technique. Since lattice dynamics is involved in the temperature dependence of some parameters of Mössbauer spectra, it seems to be possible to use them to get some information about the lattice dynamics of antiferroelectric single crystal of PbZr_1-xSn_xO₃ passing through its critical points, mainly because of a Mössbauer nuclei (Sn) implemented to the crystal lattice.