Spinodal decomposition, as opposed to nucleation and growth, is a pathway to fine dispersions of new phases. Enhanced piezoelectric performance has been reported for ferroelectrics with polymorphic phase boundary (PPB) compositions and ferroelectric nanodomains, which could be achieved by a spinodal pathway.
A few reports of spinodal decomposition in ferroelectrics have appeared recently, but no analysis of spinodal decomposition in ferroelectric crystals was found by the author.
Here, the conditions for spinodal decomposition of a paraelectric crystal to ferroelectric states are determined and critical wavelengths are identified. Predictions are made for single phase ferroelectrics and PPB ferroelectrics using the ferroelectric multi-phasefield model. A rich set of behaviours are predicted, and specific predictions are made for barium titanate, PZT and two-phase BZT-50BCT. Critical wavelengths vary from tens of unit cells to hundreds of unit cells.