Preparation of silica gels containing rare earth ions from sodium metasilicate and rare earth chloride

Several silica gels containing rare earth ions such as neodymium, samarium, or yttrium, which differed in composition, were obtained readily from sodi um metasilicate and chlorides of rare earth. The reaction was carried out a t room temperature in an aqueous solution, pH value of which was adjusted t o be below 1 at first step to generate monomeric silicic acid, and then the solution was neutralized to be pH = 7. The spectral data of IR and UV of r esulting gels suggested that rare earths dispersed well in silica phase. Th e TG-DTA analyses of gels showed characteristic exothermic peaks, which rel ated with the formation of crystals of rare earth silicates. The types of c rystals, obtained after calcination of gels at the temperature of exothermi c peaks, were influenced apparently by the composition of rare earth and si licon.