The layering effect of water on the structure of scheelite

Abstract

Density functional theory calculations of the calcium tungstate material scheelite CaWO₄ have shown that water introduced into the bulk material remains undissociated and leads to swelling and layering of the structure, a behaviour which may resemble silicate clays more than three-dimensional poly-anionic materials, but which results in a structure that is even more similar to a rare hydrous calcium carbonate phase—a finding which suggests the existence of semi-crystalline hydrous precursor phases to the dehydrated scheelite material.