Synthesis of fluorite ceria based solid solutions from mixed rare earth carbonates

摘要

The synthesis of new class of compound based on CeO_2 as pigments has been reported. The starting material used for preparation of the compound is mixed rare earth carbonate, which is an intermediate product obtained during beneficiation of monazite mineral to separate different rare earth metals. This paper presents direct use of the mixed rare earth carbonate without separation of individual rare earth oxides for pigment preparation, thereby reducing cost and improving eco-efficiency of the process. The effect of dopants, and different mineralizers on colour formation has been studied in detail by XRD, SEM and UV-vis spectrophotometer (CIELAB parameters), particle size analyzer. From this study, we optimized the conditions for the syntheses of mixed rare earth oxide by solid state reaction route to develop the brown colour pigments. Pigment properties such as moisture content, oil absorption, bleed resistance, opacity, gloss, etc., of the product has been evaluated and found to be in acceptable range. Nominal composition of the product was found to be Ce_(0.75)Pr_(0.05)Ln_(0.20)O_(1.9), where Ln includes, La, Nd, Sm, Gd.