Characterization of porous titania and ceria ceramics by small-angle neutron scattering

Titania powder was prepared by a solution based hydroxide precipitation technique using the tetrachloride precursor and ammonia as the precipitating agent. Ceria powder was prepared by homogeneous precipitation method using cerium nitrate and hexamethylenetetramine. The particle size distribution of titania and ceria powders was measured by laser light scattering. The powder particles were found to follow a log-normal size distribution and the average size of the particles for both the powders was ∼0.7 microns. Small-angle neutron scattering (SANS) was used to study the sintering behaviour and evolution of pore morphology in sintered compacts of titania and ceria by varying the sintering temperature/time. The SANS profiles were analyzed in the light of poly-disperse spherical pore model using log-normal size distribution. The pore sizes in both the ceramic compacts varied from 10 to 1000 nm and the mean value of the distribution shifted from a lower, 50 nm to a higher, 350 nm size. This trend could be attributed to both densification and grain growth occurring in the compacts with the progress of sintering. (author)