Synthesis of lanthanide molybdates via reaction of molybdenum(VI) oxide with aqueous acetate salts

Abstract

Reaction of aqueous solutions of either lanthanum or cerium acetate with molybdenum(VI) oxide (MoO3) produces a mixed lanthanide molybdate acetate, Ln(O2CCH3(MoO4) XH2O (Ln= La, Ce) that is an excellent single source precursor for stoichiometric Ln2Mo2O9. The reaction is very sensitive to the radius of the lanthanide metal used: metals with smaller radii (e.g. yttrium, praseodymium or neodymium) produce a hydroxyl molybdate product, M(OH)x(MoO4)1-x, instead of an acetate molybdate. The products were fired at high temperatures for further investigation. The products were characterized by thermal gravimetric analysis (TGA) and infrared and NMR spectroscopy. The conversion of the products to lanthanide molybdenum oxides was used to study the possibility of producing phosphors, La2Mo2O9:Ln3+ by doping lanthanum molybdenum oxides with other lanthanide metals such as praseodymium acetate. Also, fluorescence spectroscopy was run to study the doping material.