- Calcium tungstate is an inorganic compound with the chemical formula CaWO₄, composed of calcium (Ca²⁺) and tungstate (WO₄²⁻) ions. It naturally occurs as the mineral scheelite, which is an important ore of tungsten.
- Calcium tungstate typically forms colorless to white crystals with a tetragonal crystal system and is known for its high density, optical clarity, and strong luminescent properties. It is sparingly soluble in water but chemically stable under normal environmental conditions, making it valuable in scientific, industrial, and technological applications.
- One of the most significant uses of calcium tungstate is in scintillation detectors, where it serves as a scintillating crystal. When exposed to high-energy radiation, such as X-rays or gamma rays, calcium tungstate emits visible light through photoluminescence, a property that has been historically harnessed in X-ray imaging screens. In fact, before the advent of modern digital radiography, calcium tungstate was widely used in medical diagnostic equipment to enhance image brightness and reduce radiation exposure. Its ability to convert X-ray energy into visible light made it instrumental in early radiographic technology.
- In materials science and optics, calcium tungstate is valued for its optical clarity and refractive index, which make it suitable for laser and photonics applications, especially when doped with rare-earth or transition metal ions. Such doped variants are used in solid-state lasers, phosphors, and advanced lighting systems. Its luminescent properties are also exploited in various display technologies and sensor devices.
- Calcium tungstate is also of importance in geochemistry and mineralogy, as the mineral scheelite is a major source of tungsten, a metal critical for the production of hard materials, high-temperature alloys, and cutting tools. Scheelite’s fluorescence under ultraviolet light is a key identification method in tungsten ore exploration and mining.
- In addition to its optical uses, calcium tungstate has been investigated for use in catalysis and electronic devices. Its robust thermal and chemical stability make it a good candidate for use in high-temperature or corrosive environments, particularly as part of ceramic composites or as a host material in heterogeneous catalysis.
- From a safety and environmental standpoint, calcium tungstate is generally considered low in toxicity, although prolonged exposure to tungsten compounds should be controlled due to potential bioaccumulation and respiratory risks from dust inhalation. In practical use, however, calcium tungstate is considered safe under standard handling conditions.
