Size effects on the Curie temperature and spontaneous polarization in spherical particles are studied using Landau phenomenological theory. The extrapolation length is shown to be size dependent. The spatial distribution of polarization is obtained. The size dependence of the polarization is calculated whereby a size-driven phase transition is demonstrated. The Curie temperature as a function of particle size is calculated. Theoretical results are compared with the experimental in the literature and good agreement is obtained.

• Received 7 March 1994

DOI:https://doi.org/10.1103/PhysRevB.50.698