FINITE-SIZE EFFECTS IN ANTIFERROELECTRIC PBZRO3 NANOPARTICLES

We study the size dependence of the antiferroelectric-to-paraelectric phase transition in ultrafine particles of PbZrO3 (with x-ray domain s ize down to approximate to 30 nm) prepared by the sol-gel method. The phase transition was investigated by means of dielectric and thermal m easurements. The nature of the particle size dependence of various pro perties of antiferroelectric PbZrO3 was found to be generally similar to that of typical 'displacive' ferroelectrics such as PbTiO3 and BaTi O3. In both cases, a size-induced structural distortion towards the hi gh-symmetry paraelectric phase appears to dictate the behaviour of the nanoparticulate system. Nanoparticles of 'order-disorder' systems suc h as NaNO2 behave in a markedly different manner. With decreasing part icle size, we observe an increasing deviation of the dielectric respon se from the Curie-Weiss behaviour. Certain physical situations that ma y lead to the observed smearing out of the transition in nanoparticles of PbZrO3 and PbTiO3 are discussed.