Small-angle neutron scattering investigations on fractal aggregation and sintering behavior of La1-xCaxCrO3 synthesized by a combustion process

La1-xCaxCrO3 (x = 0.3) powder has been synthesized by gel combustion process. Fractal behavior of the agglomerates and pore morphology of the sintered compacts have been studied by small-angle neutron scattering. At low scattering vector (q) regime the ʹq^-Dfʹ power law variation of intensity of the powder sample and the green compact indicates that the powder particles are agglomerates and are composed of fractal aggregates. The value of the mass fractal dimension Df of these aggregates was found to be ~2.2. The Porod exponent of the scattering profiles of the sintered specimens shows deviation from its normal value of -4 to ~-3. This has been attributed due to superposition of scattering intensities from fine intra-granular pores on the scattering intensity from inter-granular pores. Loss of fractal structure of the aggregates upon heat treatment of the compacts at higher temperature has been observed. The pore size distribution gradually shifts towards higher radius size with the increase in sintering temperature due to faster elimination of finer pores.