SYNTHESIS OF LANTHANIDE ORTHOPHOSPHATE BY GLYCOTHERMAL REACTION

Glycothermal reaction of acetate hydrates of lanthanide elements with triethyl phosphate in 1,4-butanediol at 315-degrees-C afforded corresponding lanthanide orthophosphates (LnPO4). The monoclinic modification of the phosphates was obtained from the acetates of La-Eu and the tetragonal one from Tb-Lu. Gadolinium acetate yielded a mixture of the tetragonal and monoclinic modifications ; the former form of GdPO4 had been synthesized only by calcination of the monoclinic form at about 1700-degrees-C. With the decrease in the reaction temperature, the proportion of the tetragonal modification decreased. The monoclinic modification of TbPO4 was also formed at the reaction temperature 225-degrees-C together with the tetragonal form. The products were comprised of micro crystals (15-40 nm).