High-purity aluminium fluoride - obtd. by sublimation with prior admixture with complex-former to remove transition-metal impurities

摘要

Method is disclosed for preparing high-purity Al fluoride by sublimation. A complex-former is added to the crude fluoride before sublimation, which forms volatile complexes both with the Al fluoride and with transition metal impruities. The complex-former is added in amts. from about 50 ppm up to 20 wt.%. USE/ADVANTAGE - The method is used to produce high-purity aluminium fluoride for special optical glass and fibre-optic waveguides. Al fluoride can be purified in an improved manner by the use of an additive, without disadvantageous effects on the reactor material or on the progress of the reaction