Balnyh V. Technology of production of special purity sodium iodide for single crystals

The thesis is dedicated to the development of technology of production of special purity sodium iodide adapted at most for the growing of single crystals. The optimum regime for the syntheses of sodium iodide was determined, and the requirements as to the purity of initial iodine were formulated. Regimes and conditions of sodium iodide purification from impurities be means of filtration, recrystalization and washing of crystals were investigated. The possibility of production of sodium iodide with a limited content of organic impurities, meeting the requirements of crystals, quality, was determined. Constitution P-t diagram of the system “NaI-H20” in the temperature range 5- 80°C was plotted, the conditions of existence of NaI, NaI•2H2O and saturated steam were determined, and scientifically grounded requirements to the conditions of sodium iodide dehydration were formulated. The method of sodium iodide drying by sublimation and instrumentation of the process were worked out. New methods of quality control for special purity sodium iodide were proposed. The nature of hitherto unknown dehydration of sodium iodide under vacuum at high temperatures was determined. Kinetics of NaI•H2O dehydration under dynamic vacuum was investigated. Technology was developed, and commercial manufacture of special purity sodium iodide organized.