Microstructural effects on the luminescence intensity of Pr3+-doped CaTiO3

The microstructural and luminescence characteristics of solid state (SS) and sol-gel (SG) processed CaTiO3:Pi(3+) powders have been investigated as a function of the grinding time t, in the case of SS, samples and of OH/Ti(OPr)(4) molar ratios r, in the case of SG, samples. It is observed that either extended post-synthesis grinding or sol-gel syntheses operated under acid or neutral conditions lead to submicron grained microstructures, CaTiO3 + TiO2 phase mixing and finally to less efficient phosphors. The observed decrease of luminescence intensity is correlated to the presence of non-luminescent ruble and to the amount of submicron particles.