Pseudo-cubic Compounds of Alkaline Earth Oxides with Tungsten and Molybdenum Oxides

Abstract

THERE are well-recognized anhydrous tungstates of the alkaline earths calcium, strontium and barium typified by the composition RWO⁴. The mineral scheelite, CaWO⁴, is an example, and its crystal structure conforms to the tetragonal system with an axial ratio approximately 2·17¹. These tungstates are readily prepared synthetically by precipitation methods or by heat treatment of the appropriate mixtures of the alkaline earth carbonate with tungsten oxide. Calcium tungstate in particular is an important inorganic luminescent compound, and is utilized for a variety of purposes, for example, as an ingredient of X-ray intensifying screens.