Barium tungstate is an inorganic chemical compound of barium and the tungstate anion. It is a white crystalline solid that is known for its high density, which makes it useful in a variety of applications. It can be used as a frequency shifter in laser technology. It has uses in X-ray photography and as a pigment.
Properties
Barium tungstate has a high density compared to other common materials, which is useful in applications requiring heavy substances. It has a high atomic number and is used in scintillation detectors for radiation detection, particularly in X-ray and gamma-ray spectrometry. It is also known for its optical properties, making it useful in certain optical applications, such as lasers and optical lenses.
- Chemical formula: BaWO4
- Molar mass: 385.16 g·mol−1
- Appearance: white solid
- Density: 5.04 g·cm−3 (25 °C) 7.26 g·cm−3 (high pressure form)
- Melting point: 1502 °C
- Solubility in water: insoluble
Synthesis
Barium tungstate can be obtained from the precipitation reaction between barium nitrate and ammonium paratungstate or sodium tungstate.
Ba(NO3)2 + Na2WO4 → BaWO4↓ + 2 NaNO3
It is a white solid, which at normal conditions forms tetragonal crystals similar to scheelite, CaWO4. Under pressures above 7 GPa, the compound undergoes transformation to a monoclinic structure similar to fergusonite, YNbO4.
Occurrence
Barium tungstate occurs naturally as the mineral schörlite. Schörlite is rare but can be found in some mineral deposits, typically associated with tungsten-bearing ores. It forms through the reaction between barium salts and tungsten-containing compounds, which may occur in specific geological conditions.
Barium tungstate is mostly produced synthetically for industrial and scientific purposes. It can be synthesized through the precipitation method using barium salts and tungsten compounds, often at high temperatures.
Applications
- Scintillation Detectors: BaWO₄ is used in scintillation crystals to detect high-energy radiation, such as X-rays and gamma rays. When exposed to radiation, barium tungstate emits light that can be detected and measured.
- X-ray and Gamma-ray Detection: Due to its high atomic number and density, BaWO₄ is used in devices for detecting radiation, particularly in medical imaging and nuclear industry applications.
- Luminescent Materials: Barium tungstate is sometimes used in the production of phosphors and luminescent materials because it emits visible light when irradiated with gamma rays.
- X-ray Scintillators: Due to its properties, BaWO₄ is commonly used in X-ray and CT scanning equipment to improve the accuracy of radiation detection.
- Optical Applications: The compound is used in optical lenses and components due to its excellent light transmission properties, especially in the infrared spectrum.
Safety Considerations
Barium compounds can be toxic if ingested or inhaled in large amounts. Proper safety measures should be taken when handling barium tungstate to avoid exposure to barium dust or fumes.
