| abstract |
Since the conventional rare earth metal compound sol is an organic sol, an explosion-proof device is necessary in the manufacture and use of it, and it was difficult to suppress manufacturing cost low.n n n The water-soluble rare earth metal compound sol according to claim 1 of the present invention is a carboxylic acid having three or more carbonyl groups and Sc, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, A rare earth metal compound that satisfies the relationship of 1.2 to 3 in a molar ratio (carbonyl group / rare earth metal) to at least one rare earth metal selected from Er, Tm, Yb, and Lu is dispersed in water. |