Synthesis and sintering of nanocrystalline barium titanate powder under non-isothermal conditions. VI. Structure, grain boundaries, and dielectric properties of barium titanate obtained by various sintering methods

The grain boundary structure of barium titanate obtained by controlled-rate sintering (CRS) and high-pressure sintering (HPS), and the dependence of d ielectric properties on grain size and consolidation method were studied. I t was shown that sintering without the application of pressure leads to a d iffusion-controlled formation of equilibrium grain boundaries with minimal impedance factor, which minimally decrease the dielectric constant of the c eramics. HPS results in the formation of non-equilibrium grain boundaries w hich have a large free volume, and which substantially decrease the dielect ric constant. The Curie-Weiss constant was analyzed from the viewpoint of a matrix structural model, and a "brick-wall" model.