A model for the description of precursor order clusters at ferroelectric phase transitions is proposed. In this model the cluster walls separating the paraelectric and ferroelectric regions are obtained as kink solutions of the nonlinear dynamic equations including a damping term. The cases of first- and second-order phase transitions and of the tricritical point are considered. It is shown that the precursor order clusters of this type bring about the intrinsic central peak at the low-temperature first-order ferroelectric phase transition in proustite (Ag3AsS3). The analysis of the 75As nuclear quadrupole resonance and spin-lattice relaxation data for proustite indicates that the central peak for the hydrostatic pressures p ≤ 3.2 kbar is apparently caused by pretransitional heterophase fluctuations which are described by the above-mentioned model. Beyond the pressure-induced tricritical point at p > 3.2 kbar the central peak is associated with the precursor order clusters of another type also described by this model. The features of spin-lattice relaxation near first-order phase transitions, in particular, in proustite are considered.
|Number of pages
|Physica B: Physics of Condensed Matter & C: Atomic, Molecular and Plasma Physics, Optics
|Published - Jul 1984
ASJC Scopus subject areas
- General Engineering