Growth of Pure Single Crystals of Alkali Halides and Alkaline Earth Fluorides

The final report covers the design of ion selective filters and development of an ion exchange purification system for potassium bromide. The system consists of an ion selective filter for passage of potassium ions and a bromide anion exchange system for reduction of anionic impurities. Because of the high ionic strength of the solutions used and particularly their ability to hydrolyze amide and ester bonds, limitations are imposed on the materials that can be used for construction of those parts of the systems that contact these solutions. Certain addition polymers are more promising for construction of the components of such a system than others, these are discussed in the body of the report. A special group of components have been designed and assembled to provide the fittings, valves, electrode chambers, sampling valves, columns and filters necessary for a closed purification system. The preparation of the resins for use in such a system required that their conversion to the forms required for purification of KBr, require that the reactions for this conversion go almost to completion. The extent of conversion of the resins affect the operational characteristics of the system and are discussed in this report. The product of the initial purification is a strongly acid KBr solution and the techniques were developed to minimize external contamination during reduction of the purified salt solution to a solid. The final purification step made during the growth of the crystal is treatment with a reactive gas. A greaseless reactive gas manifold was constructed and several reactive gas treatments were used in an attempt to purify the KBr.