Incomplete ferroelectricity in SrTi18O3

Motivated by recent experiments demonstrating suppression of ferroelectricity with pressure in (SrTiO3)-O-18, the dynamics of the phase transition mechanism are reinvestigated within a nonlinear polarizability model. For temperatures far above the phase transition polar micro domains are formed which increase in size with decreasing temperature to freeze out at T-c without forming long range order. Experimentally, soft mode dynamics are simultaneously observed, evidencing that displacive and order/disorder features coexist. In the ferroelectric phase both components persist whereby an incomplete and inhomogeneous ferroelectric state is formed.