Rational Combination of the Dissolution of Some Inorganic Compounds of Rare-Earth Elements with the Determination of Chemical Forms of Major Constituents in These Compounds

摘要

It was found that the major constituents (F~- and S~(2-)) in fluorides, sulfides, and sulfofluorides of rare-earth elements, and europium(II) in europium fluoride, can be determined titrimetrically. Peculiarities of thedecomposition and analysis of initial samples of these compounds and samples after high-temperature treat-ment in vacuum were considered. The analytical procedures are based on the combination of the decomposition of the test materials using solutions of iodine (determination of S~(2-)), boric acid (determination of F~-), and vana-dium(V) salts (determination of europium(II) salts) and the final titration of excess reagents that selectively reacted with a chemical form of the analyte. Potentiometry with an ion-selective electrode was also used in the determination of fluoride ions. The total concentration of rare-earth elements was determined by chelatometry.