Surf Wiki
Save to docs
general/cadmium-compounds

From Surf Wiki (app.surf) — the open knowledge base

Cadmium tungstate

| NFPA-H = | NFPA-F = | NFPA-R =

Cadmium tungstate (CdWO4 or CWO), the cadmium salt of tungstic acid, is a dense, chemically inert solid which is used as a scintillation crystal to detect gamma rays. It has density of 7.9 g/cm3 and melting point of 1325 °C. It is toxic if inhaled or swallowed. Its crystals are transparent, colorless, with slight yellow tint. It is odorless. Its CAS number is 7790-85-4. It is not hygroscopic.

The crystal is transparent and emits light when it is hit by gamma rays and x-rays, making it useful as a detector of ionizing radiation. Its peak scintillation wavelength is 480 nm (with emission range between 380 and 660 nm), and efficiency of 13000 photons/MeV. It has a relatively high light yield, its light output is about 40% of NaI(Tl), but the time of scintillation is quite long (12−15 μs). It is often used in computed tomography. Combining the scintillator crystal with externally applied piece of boron carbide allows construction of compact detectors of gamma rays and neutron radiation.

Cadmium tungstate was used as a replacement of calcium tungstate in some fluoroscopes since the 1940s. Very high radiopurity allows use of this scintillator as a detector of rare nuclear processes (double beta decay, other rare alpha and beta decays) in low-background applications. For example, the first indication of the natural alpha activity of tungsten (alpha decay of 180W) was found in 2003 with CWO detectors. Due to different time of light emission for different types of ionizing particles, the alpha-beta discrimination technique has been developed for CWO scintillators.

Cadmium tungstate films can be deposited by sol-gel technology. Cadmium tungstate nanorods can be synthesized by a hydrothermal process.

Similar materials are calcium tungstate (scheelite) and zinc tungstate.

It is toxic, as are all cadmium compounds.

References

References

  1. {{PGCH. 0087
  2. "Cadmium tungsten oxide (CdWO4)". CAS Common Chemistry.
  3. Burachas S. F.. (1996). "Large volume CdWO4 crystal scintillators". Nucl. Instrum. Methods Phys. Res. A.
  4. (2021). "Patterson Hand-Held Fluoroscope (ca. 1940s)". Oak Ridge Associated Universities.
  5. Kroeger, F. A.. (1948). "Some Aspects of the Luminescence of Solids". Elsevier.
  6. Bardelli L.. (2006). "Further study of CdWO4 crystal scintillators as detectors for high sensitivity 2β experiments: Scintillation properties and pulse-shape discrimination". Nucl. Instrum. Methods Phys. Res. A.
  7. Danevich F. A.. (2003). "α activity of natural tungsten isotopes". Phys. Rev. C.
  8. Fazzini T.. (1998). "Pulse-shape discrimination with CdWO4 crystal scintillators". Nucl. Instrum. Methods Phys. Res. A.
  9. (September 2006). "Hydrothermal synthesis and characterization of CdWO4 nanorods". Journal of the American Ceramic Society.
Info: Wikipedia Source

This article was imported from Wikipedia and is available under the Creative Commons Attribution-ShareAlike 4.0 License. Content has been adapted to SurfDoc format. Original contributors can be found on the article history page.

cadmium-compounds tungstates phosphors-and-scintillators
Want to explore this topic further?

Ask Mako anything about Cadmium tungstate — get instant answers, deeper analysis, and related topics.

Research with Mako

Free with your Surf account

Content sourced from Wikipedia, available under CC BY-SA 4.0.

This content may have been generated or modified by AI. CloudSurf Software LLC is not responsible for the accuracy, completeness, or reliability of AI-generated content. Always verify important information from primary sources.

Report