Glasses on the basis of heavy metal fluorides

In this review, the information on glass-forming fluoride systems is presented, and the main methods for synthesizing glasses on the basis of fluorides of the metals of Groups I–IV, their physicochemical properties, techniques for producing fibers and areas of application, and the techniques for purifying them from undesired impurities are discussed. Modern materials science studies in the area of fluoride glasses are aimed at searching for glasses activated with rare-earth elements (REEs) with a broad IR transmission range and high optical homogeneity with the purpose of creating efficient active optical media in a wide spectral range, as well as converters of IR radiation into the visible range for enhancing the efficiency of solar cells and exciting photocatalysts. The analysis of the influence of impurities on the optical transparency, crystallization, and phase purity of the glasses under study is presented. The methods for the deep purification of the initial substances for preparing fluoride glasses with the minimum content of impurities are considered. Original procedures for synthesizing fluorides of elements and glasses free from oxygen-containing impurities are created on the basis of physicochemical studies of the interactions of fluorinating agents with the components of fluoride glasses.