Abstract
Using Landau theory, the influence of size on the dielectric behaviour of ferroelectric films, cylinders and spheres has been investigated. For cylinders and spheres, a size-driven phase transition occurs and the dielectric susceptibility is always enhanced at small size. However for films, whether there is a size-phase transition depends on the surface ferroelectricity. Our calculations are in qualitative agreement with measurements on barium titanate and lead titanate.