Effect of particle size distribution on functional properties of Ce0.9Y0.1O2-d ceramics

Abstract This paper has investigated the dependence of the mechanical and electrical properties of ceramics Ce0.9Y0.1O2-d (CeY) on changes in the proportion of submicron size particles in a powder with bimodal particle size distribution. The powder was prepared by mixing the products of sol-gel (submicron size fraction with average size of 0.2 μm and specific surface area of 39.52 m2/g) and solid-state synthesis (micron size fraction with average size of 5.68 μm and specific surface area of 4.81 m2/g) in a certain ratio to get different proportion of the fractions. All ceramics samples were formed by isostatic pressing with further annealing under identical conditions. The microstructure of ceramic samples was studied using scanning electron microscopy and static volumetric analysis. The impedance spectroscopy method has determined the temperature dependencies of the grain boundary resistance fraction, which are strongly related to the particle size distribution. The microhardness of samples was determined by the Vickers method. A nonlinear change of mechanical and electrical properties was found for the samples having approximately 20% content of submicron size particles. The dependence of the total electrical conductivity and the dependence of the microhardness on the particle size distribution possess the maxima and minima points for these compositions, respectively. The particle size distribution of powders has a strong impact on the ceramics formation process and allows to control the microstructure and physical properties of materials. We have proposed the ceramics model of “arched structure”, formed by bimodal compositions sintering, which allows to predict the properties of ceramics with other compositions.