Tungstates

Tungstates are chemical compounds that contain the tungstate anion, WO4^2−, or related tungsten(VI) oxoanions derived from tungstic acid H2WO4. The central atom is tungsten in the +6 oxidation state. The basic building block is the tetrahedral [WO4]2− anion; in aqueous solution these units can link through shared oxygens to form larger polyoxometalate species, such as metatungstate and paratungstate, depending on pH and concentration.

Tungstate minerals include scheelite, CaWO4, and wolframite, (Fe,Mn)WO4, which are the principal ore minerals for tungsten. A wide range of tungstate salts are known, including soluble alkali and alkaline earth tungstates such as Na2WO4 and CaWO4, as well as less soluble salts like BaWO4 and PbWO4.

Applications vary. Tungstates are used in pigments and phosphors; for example, calcium tungstate and zinc tungstate are used in phosphor materials, and lead tungstate PbWO4 is a widely used scintillator in particle physics detectors. Tungstate compounds also serve as precursors to tungsten oxide materials (WO3) and find use as catalysts and in ceramics and optics.

In summary, tungstates describe a family of compounds centered on the WO4 tetrahedron, ranging from mineral ores to functional materials with applications in lighting, imaging, and catalysis.