SANS study of fractal microstructure and pore morphology in porous titania

Abstract

High pure titania powder was prepared by solution based hydroxide precipitation technique using chloride precursor and ammonia as precipitating agent. Effect of sintering temperature on fractal microstructure and pore size distribution in pressed compacts of titania with graded porosity obtained by firing at various temperatures have been investigated by small-angle neutron scattering technique. The results showed that the powder granules are aggregates and composed of fine primary particles of average size 2.5 nm. The granules possess a fractal structure of mass fractal dimension 2.4. With increase in sintering temperature the granules gradually lost their fractal microstructure and the intra- and inter-granular pore size distributions in the compacts shifted towards higher radius size with a decrease in porosity. A power law size distribution for the intra-granular fine pores and lognormal size distribution for the inter-granular coarse pores were used for fitting the model.