Densification and enhanced polarisation in lead zirconate titanate sol–gel thin films

Isopressing a PbZr0.3Ti0.7O3 sol–gel coating prior to thermally induced crystallisation leads to increased remanent polarisation (Pr) values for optimum compaction pressures of ∼125 MPa. The value of Pr increases from 25 μC cm−2 for a single layer 0.3 μm porous film prepared in the normal manner, to 34 μC cm−2 for an equivalent 0.2 μm dense film. Compaction pressures >135 MPa lead to little further increase in film density, but Pr decreases to values below those of non-pressed porous samples. The trends in polarisation are attributed to the balance between the beneficial effects of decreased porosity and the detrimental effects of increased strain levels in the films.