Correlation between the microstructure of ferroelectric ceramics and theirchemical and phase composition, the degree of perfection of the crystal structure and the preparation conditions

The correlation between crystallite sizes of ferroelectric ceramics and spo ntaneous deformation of the crystal unit cell was considered for two cases: 1) in varying concentrations of solid solutions of the systems based on Na NbO3 and PbTiO3-PbZrO3, and 2) in the individual compositions of the above systems with the crystallite size varying with the preparation conditions. It is shown that in the first case there is a reciprocal dependence between the homogeneous deformation parameter delta characterizing the spontaneous deformation of the crystal unit cell and the crystallite sizes (d) over ba r. In the second case delta varies with (d) over bar.