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CALCIUM TUNGSTATE

Calcium tungstate is an inorganic compound with the chemical formula CaWO₄, naturally occurring as the mineral scheelite and widely known for its high density, chemical stability, and strong luminescent properties.
Calcium tungstate is best known for its ability to fluoresce under ultraviolet and X-ray exposure, emitting a bright blue-white glow, making it critical for applications such as X-ray screens, fluorescent lamps, and scintillation detectors.
Industrially, calcium tungstate serves as an important intermediate in the production of tungsten metal and tungsten alloys, while also being explored for use in optical materials, laser host crystals, and medical imaging technologies.

CAS Number: 7790-75-2
EC Number: 232-215-3
Molecular Formula: CaO4W
Molecular Weight: 287.92

Synonyms: MFCD00010913, Calcium tungstate Powder, FDMFQOCGNBYKPY-UHFFFAOYSA-N, Tungstate calcium (T-4)-lead-doped, AKOS015916113, Calcium tungstate, 99.9% -325 mesh, Q1026374, 232-219-4, 7790-75-2, Calcium dioxido(dioxo)tungsten, Calcium tungstate, Calcium tungstate(VI), Calciumdioxido(dioxo)wolfram, Dioxo(dioxydo)tungstène de calcium, MFCD00010913, Tungsten, diolatodioxo-, calcium salt (1:1), 113933-94-1, 210909-23-2, 68784-53-2, 825-25-2, 98%, calcium dioxotungstenbis(olate), Calcium tetraoxotungstate, Calcium tungstate, 99.9% -325 mesh, calcium tungsten oxide, Calcium tungsten oxide (CaWO4), CALCIUM WOLFRAMATE, calciumtungstate, Scheelite, [Wiki]link-icon, TUNGSTATE (WO42-) CALCIUM (1:1) (T-4)- LEAD-DOPED, Tungstate (WO42-), calcium (1:1), (β-4)-, Tungstate calcium (T-4)-lead-doped, Tungstic acid (H2WO4) calcium salt (1:1)

Calcium tungstate is an optical material, which can be used as a laser host material for a variety of electronic applications.
Calcium tungstate has a scheelite structure with luminescence, and thermo-luminescence properties.

Calcium tungstate is one of the most important X-ray luminophores, i.e. when exposed to X-rays it appears blue.
Calcium tungstate is also impermeable to X-rays. These properties make it particularly suitable for use in medical technology.

Calcium tungstate is used in transfer films in X-ray equipment or as a contrast agent.
Calcium tungstate is a very important chemical raw material.

Calcium tungstate is mainly used to produce tungsten products such as tungsten trioxide, iron tungsten, alloy steel, cemented carbide, tungsten material, tungsten wire and tungsten alloy.
Calcium tungstate is also used in fluorescent coatings, light screen tubes for photography, medicine, X-ray photographs, and fluorescent lamps.

Calcium tungstate is a high purity, low trace tungstate represented by the formula CaWO4.
Calcium tungstate is used chiefly in screens for radiography as a contrast agent, in luminous paint, and in fluorescent lamps.

Calcium tungstate is an inorganic compound with the chemical formula CaWO₄, commonly encountered as a white or colorless crystalline solid.
Calcium tungstate naturally occurs as the mineral scheelite, an important ore of tungsten.

Calcium tungstate is best known for its ability to fluoresce under ultraviolet light, emitting a bright blue-white glow, a property that has led to its early use in X-ray screens and fluorescent lamps.
Calcium tungstate is insoluble in water and most organic solvents but can dissolve in strong acids.

Industrially, Calcium tungstate is used in the production of tungsten metal and tungsten-containing alloys by serving as an intermediate in extraction and refining processes.
Calcium tungstate's high density and luminescent properties make it valuable in applications such as scintillation detectors for radiation detection, as well as in specialized optical materials.

Due to its excellent chemical stability and mechanical strength, Calcium tungstate is also explored in modern technologies like medical imaging and laser devices.
Overall, Calcium tungstate remains an important material due to its combination of optical activity, durability, and role in tungsten metallurgy.

Market Overview of Calcium Tungstate:
The global Calcium tungstate market is experiencing steady growth, driven by its diverse applications across medical imaging, radiation detection, metallurgy, and advanced lighting technologies.
Calcium tungstate's unique properties—such as high density, chemical stability, and luminescence—make it indispensable in various industrial and technological sectors.

Market Drivers:

Medical Imaging and Diagnostics:
Calcium tungstate's exceptional luminescent properties have historically made it a critical component in X-ray intensifying screens.
Calcium tungstate's ability to convert X-rays into visible light enhances image clarity while reducing patient exposure to radiation.
The ongoing demand for advanced diagnostic tools, especially in emerging economies, continues to bolster the market.

Radiation Detection and Security:
In the realm of radiation detection, Calcium tungstate is utilized in scintillation detectors, converting high-energy radiation into visible light signals.
This application is vital in nuclear medicine, security scanning, and scientific research, contributing to Calcium tungstate's market growth.

Tungsten Extraction and Metallurgy:
Serving as an essential intermediate in tungsten production, Calcium tungstate is processed to obtain pure tungsten metal.
This metal is crucial for manufacturing hard metals, alloys, and cutting tools, with demand rising in sectors like aerospace, automotive, and construction.

Advanced Lighting Solutions:
Calcium tungstate's luminescent properties are harnessed in the production of fluorescent lights and compact fluorescent lamps (CFLs).
As the global emphasis on energy-efficient lighting solutions intensifies, Calcium tungstate's role in this sector becomes increasingly significant.

High-Performance Materials:
In metallurgy, Calcium tungstate is used as an additive in steel production to enhance strength and wear resistance.
This application is gaining traction, particularly in the construction and automotive industries, where durable materials are paramount.

Market Outlook:
The Calcium tungstate market is poised for continued expansion, underpinned by its multifaceted applications and the growing demand for high-performance materials.
Technological advancements in medical imaging, increased focus on security and radiation detection, and the push for energy-efficient lighting solutions are expected to drive market growth.
Additionally, Calcium tungstate's role in tungsten extraction aligns with the rising need for durable metals in various industries.

However, market participants must navigate challenges such as raw material availability, environmental regulations, and competition from alternative materials.
Strategic investments in research and development, coupled with sustainable practices, will be crucial for stakeholders aiming to capitalize on the market's potential.

In summary, Calcium tungstate's unique properties and versatile applications position it as a valuable compound in the global market, with promising growth prospects across multiple sectors.

Applications of Calcium Tungstate:
Calcium tungstate can be used in the fabrication of a radio-sensitizer for cancer radiotherapy applications.
Calcium tungstate can also be used as a catalyst for the oxidation of organic substrates with hydrogen peroxide.
Calcium tungstate is mainly used to produce tungsten products such as tungsten trioxide, iron tungsten, alloy steel, cemented carbide, tungsten material, tungsten wire, and tungsten alloy and also used in fluorescent coatings, light screen tubes for photography, medicine, X-ray photographs, and fluorescent lamps.

Calcium tungstate finds application across various industries owing to its unique combination of high density, chemical stability, and strong luminescent properties.
In the medical field, Calcium tungstate is historically significant for its use in X-ray intensifying screens, where its ability to fluoresce upon exposure to X-rays dramatically enhanced imaging quality while reducing patient radiation exposure.

In radiation detection, Calcium tungstate is utilized in scintillation detectors, playing a critical role in nuclear medicine, security scanning, and scientific research by converting high-energy radiation into visible light signals.
Calcium tungstate also serves as an important intermediate in the extraction of tungsten metal, which is essential for producing high-strength alloys, electrical filaments, and heavy-duty industrial tools.

Additionally, Calcium tungstate's optical properties make it a candidate for use in specialized laser devices and photonic materials.
In gemology, natural crystals of Calcium tungstate, known as scheelite, are occasionally cut and polished as gemstones, prized for their strong blue-white fluorescence under ultraviolet light.

Furthermore, because of its high density, Calcium tungstate is explored as a material for radiation shielding in both medical and industrial protective equipment.
These diverse applications highlight the versatility and enduring value of Calcium tungstate in technological and scientific advancements.

Uses of Calcium Tungstate:
Calcium tungsten oxide is used as a luminophore.
Calcium tungstate can be ued for preparing screens for x-ray observations and photographs; in luminous paints; in scintillation counters.

Calcium tungstate is well known as the phosphor that emits light in λ: 310–700 nm under the excitation light in λ: 220–300 nm.
The peak wavelength is positioned at 440 nm, causing it to give off a blue color.

Calcium tungstate is used in a variety of specialized industrial, scientific, and medical applications, mainly due to its luminescent, high-density, and chemically stable properties:

X-ray Imaging:
Calcium tungstate was historically one of the first materials used in X-ray intensifying screens, where it fluoresces brightly upon exposure to X-rays, significantly reducing the radiation dose needed for medical imaging.

Scintillation Detectors:
Calcium tungstate's ability to emit visible light upon exposure to ionizing radiation makes Calcium tungstate valuable in scintillation counters used for detecting and measuring radiation levels in scientific, medical, and nuclear fields.

Tungsten Extraction:
Calcium tungstate serves as an important intermediate in the production of tungsten metal.
Calcium tungstate is processed through chemical methods to obtain pure tungsten for use in hard metals, filaments, and high-strength alloys.

Optical and Photonic Applications:
Due to its optical properties, Calcium tungstate is explored in the development of specialized optical materials, lasers, and photonic devices.

Jewelry and Gemology:
Naturally occurring Calcium tungstate (scheelite) is sometimes cut and used as a gemstone, valued for its brilliant fluorescence and aesthetic appeal.

Radiation Shielding:
Because of its high density, Calcium tungstate can be incorporated into materials designed to provide protection against radiation, particularly in medical and industrial settings.

Scientific Research:
Calcium tungstate crystals are used in experimental studies related to luminescence, crystallography, and material science.

Features of Calcium Tungstate:

High Density:
Calcium tungstate possesses a high density (approximately 6.06 g/cm³), making it highly effective for radiation shielding and detection applications.

Luminescence:
Calcium tungstate exhibits strong blue-white fluorescence when exposed to ultraviolet (UV) light or X-rays, a property that is fundamental to its use in medical imaging and scintillation detectors.

Chemical Stability:
Calcium tungstate is chemically stable under normal environmental conditions.
Calcium tungstate is resistant to decomposition and maintains its structure even under exposure to heat and radiation.

Insolubility in Water:
Calcium tungstate is practically insoluble in water and most organic solvents, ensuring long-term durability and resistance to leaching when used in coatings and industrial applications.

Hardness:
On the Mohs hardness scale, Calcium tungstate registers around 4.5–5, giving it moderate hardness suitable for both industrial and decorative uses (such as gemstone cutting in the form of scheelite).

Good Thermal Stability:
Calcium tungstate maintains structural and optical properties over a wide temperature range, making it suitable for high-energy physics experiments, lasers, and radiation environments.

Non-toxicity:
Compared to many other heavy metal compounds, Calcium tungstate is considered relatively non-toxic, broadening its usability in medical and industrial applications.

Optical Transparency:
Crystals of Calcium tungstate can be optically transparent, which is valuable in certain advanced optical and photonic applications.

Natural Occurrence:
Calcium tungstate naturally occurs as scheelite, providing an accessible source of the material for extraction and industrial use without the need for complete synthetic production.

Production of Calcium Tungstate:
Calcium tungstate is typically produced through a chemical reaction between soluble calcium salts and soluble tungstate salts under controlled conditions.
One of the most common methods involves reacting calcium chloride (CaCl₂) or calcium nitrate (Ca(NO₃)₂) with sodium tungstate (Na₂WO₄) in an aqueous solution.
During the reaction, insoluble Calcium tungstate precipitates out of the solution as a fine white powder.

The basic reaction can be represented as:
CaCl2+Na2WO4→CaWO4↓+2NaCl

Alternatively, Calcium tungstate can also be synthesized directly by reacting calcium oxide (CaO) or calcium hydroxide (Ca(OH)₂) with tungstic acid (H₂WO₄) under controlled pH and temperature conditions to ensure high purity and desired particle morphology.

After precipitation, the product is filtered, washed thoroughly to remove soluble impurities (such as sodium chloride), and then dried at moderate temperatures.
The drying step must be carefully controlled to preserve the crystalline structure of Calcium tungstate.
Depending on Calcium tungstate's intended application (e.g., scintillation, metallurgy, or optical use), further post-processing such as milling to achieve specific particle sizes or sintering to form dense bodies may be employed.

In industrial production, attention is given to controlling crystal size, shape, and purity, as these factors critically influence the luminescent efficiency, density, and mechanical properties of the final product.
Modern manufacturing processes may also incorporate doping with small amounts of rare earth elements (e.g., europium) to enhance the luminescent properties for specialized optical or detection applications.

Production Methods:
A single crystal is grown from melt by the Czochralski method.
Rare earth ions are easy to incorporate into the crystal during growth.

Fluorescent films are deposited on a glass substrate through vacuum evaporation using a W filament heated at 2000℃ for about 3 min, followed by thermal annealing in oxygen at 550℃ for 2 h.
The film becomes crystalline through this thermal annealing.

Synthesis of Calcium Tungstate:
Calcium tungstate is synthesized through a simple double displacement (precipitation) reaction between a soluble calcium salt and a soluble tungstate salt in aqueous solution.
The process typically involves mixing solutions of calcium chloride (CaCl₂) or calcium nitrate (Ca(NO₃)₂) with sodium tungstate (Na₂WO₄) under ambient conditions.
Upon mixing, Calcium tungstate precipitates as a white crystalline solid because of its very low solubility in water.

The general reaction is:
Cacl2+Na2WO4→CaWO4↓+2NaCl

Alternatively, Calcium tungstate can also be synthesized by reacting calcium hydroxide (Ca(OH)₂) or calcium oxide (CaO) with tungstic acid (H₂WO₄):
Ca(OH)2+H2WO4→CaWO4+2H2O

In a typical laboratory or industrial procedure, the two reactant solutions are combined slowly under constant stirring to promote uniform nucleation and growth of Calcium tungstate crystals.
The pH of the solution is usually maintained in a neutral to slightly basic range to favor efficient precipitation.
After complete reaction, the precipitated Calcium tungstate is separated by filtration, thoroughly washed with deionized water to remove soluble byproducts (like NaCl), and dried at controlled temperatures to preserve its crystalline structure.

The characteristics of the resulting Calcium tungstate, such as particle size, morphology, and crystallinity, can be tuned by adjusting reaction conditions including reactant concentration, temperature, pH, and stirring rate.
High-purity and uniform particle size Calcium tungstate is essential for applications in scintillation detectors, medical imaging, and photonic devices.

History of Calcium Tungstate:
Calcium tungstate was first discovered in the late 18th century as part of the early exploration of tungsten minerals.
The mineral form of Calcium tungstate, known as scheelite, was identified by Swedish chemist Carl Wilhelm Scheele around 1781, who also contributed significantly to the understanding of tungstic acid.
Later, in 1783, Juan José and Fausto Elhuyar, Spanish chemists, successfully isolated the element tungsten from scheelite, cementing the mineral's importance in the history of inorganic chemistry and metallurgy.

During the early 20th century, Calcium tungstate gained industrial prominence with the invention of X-ray intensifying screens.
Calcium tungstate's strong fluorescence under X-rays allowed it to convert X-rays into visible light, thereby enhancing the brightness and reducing the radiation exposure required for medical imaging.
This application marked one of the first practical uses of Calcium tungstate beyond mineralogy and metallurgy.

Over the decades, the role of Calcium tungstate expanded into fields such as scintillation detection, tungsten extraction, advanced optical materials, and radiation shielding.
With the continuous advancement in medical technologies, nuclear science, and material engineering, Calcium tungstate has remained a crucial material, valued for its stability, density, and optical properties.
Today, Calcium tungstate continues to be studied and applied in cutting-edge fields such as high-energy physics, medical diagnostics, and next-generation radiation detectors.

Handling and Storage of Calcium Tungstate:
Calcium tungstate should be handled in a well-ventilated area to minimize dust formation.
Direct contact with Calcium tungstate (skin, eyes) and inhalation of airborne particles should be avoided.

Operators must use appropriate personal protective equipment (PPE) such as gloves, protective clothing, and safety goggles.
For storage, Calcium tungstate should be kept in tightly closed containers, in a cool, dry, and well-ventilated location, away from incompatible substances like strong acids.
Containers must be labeled properly, and storage areas should be designed to prevent moisture contamination.

Reactivity and Stability of Calcium Tungstate:
Calcium tungstate is chemically stable under normal temperatures and pressures.
Calcium tungstate does not polymerize or react dangerously under ambient conditions.

However, Calcium tungstate can react with strong acids, resulting in the release of toxic tungsten compounds or tungstic acid.
Calcium tungstate is resistant to heat and maintains its chemical structure even at elevated temperatures, but care should be taken to avoid exposure to acidic vapors or highly corrosive environments.

First Aid Measures of Calcium Tungstate:

Inhalation:
Move the affected person to fresh air.
Seek medical attention if breathing difficulty or irritation persists.

Skin Contact:
Wash the affected area immediately with plenty of water and soap.
Remove contaminated clothing.
If irritation develops or persists, seek medical advice.

Eye Contact:
Rinse eyes immediately with plenty of clean water for at least 15 minutes, lifting the eyelids occasionally.
Seek medical attention if irritation continues.

Ingestion:
Rinse the mouth thoroughly with water.
Do not induce vomiting unless instructed by medical personnel.
Seek immediate medical attention.

Firefighting Measures of Calcium Tungstate:

Although Calcium tungstate itself is non-flammable, in the event of a fire involving Calcium tungstate:
Use extinguishing media appropriate for surrounding fires, such as water spray, dry chemical, carbon dioxide, or foam.
Firefighters should wear full protective clothing and self-contained breathing apparatus (SCBA) to avoid inhaling any decomposition fumes.
Avoid spreading dust from disturbed material during firefighting operations.

Accidental Release Measures of Calcium Tungstate:
Evacuate the area and ensure proper ventilation.
Avoid creating airborne dust.

Wear suitable personal protective equipment.
Carefully sweep or vacuum Calcium tungstate without generating dust and place it in a properly labeled, sealable container for disposal according to local regulations.

Prevent material from entering drains, surface waters, or soil.
Clean the affected area thoroughly with water after material collection.

Exposure Controls / Personal Protective Equipment of Calcium Tungstate:

Engineering Controls:
Use local exhaust ventilation to minimize airborne dust concentrations.
Ensure work areas are well-ventilated.

Personal Protective Equipment (PPE):

Respiratory Protection:
Use a NIOSH-approved particulate respirator if dust levels exceed occupational exposure limits.

Eye Protection:
Use safety goggles or face shields to protect against dust particles.

Skin Protection:
Wear chemical-resistant gloves and protective clothing to prevent prolonged skin contact.

Hygiene Measures:
Wash hands and face thoroughly after handling.
Do not eat, drink, or smoke while handling Calcium tungstate.
Remove contaminated clothing and wash it before reuse.

Identifiers of Calcium Tungstate:
Chemical Formula: CaWO₄
Empirical Formula: CaO·WO₃
Molar Mass: 287.93 g/mol
CAS Number: 7790-75-2
EC Number: 232-215-3
PubChem CID: 24543
UN Number: Not classified as hazardous (No UN number)
InChI: InChI=1S/Ca.O4W/c;1-5(2,3)4/q+2;-2
InChI Key: QJFQKZIEVGEADB-UHFFFAOYSA-N
SMILES: [Ca+2].[O-][W](=O)(=O)[O-]
EINECS Number: 232-215-3
HS Code: 2841.90 (Salts of peroxometallic acids, Tungstates)

Linear Formula: CaWO4
CAS Number: 7790-75-2
Molecular Weight: 287.92
EC Number: 232-219-4
MDL number: MFCD00010913
UNSPSC Code: 12352300
PubChem Substance ID: 24854944
NACRES: NA.23

CAS No.: 7790-75-2
CBNumber:CB6135863
Molecular Formula: CaO4W
Molecular Weight: 287.92
MDL Number: MFCD00010913

Linear Formula: CaWO4
Pubchem CID: 123264
MDL Number: MFCD00010913
EC No.: 232-219-4
IUPAC Name: calcium dioxido(dioxo)tungsten
Beilstein/Reaxys No.: N/A
SMILES: [Ca+2].[O-][W]([O-])(=O)=O
InchI Identifier: InChI=1S/Ca.4O.W/q+2;;;2*-1;
InchI Key: FDMFQOCGNBYKPY-UHFFFAOYSA-N
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Properties of Calcium Tungstate:
form: powder
density: 6.06 g/mL at 25 °C (lit.)
SMILES string: [Ca++].[O-][W]([O-])(=O)=O
InChI: 1S/Ca.4O.W/q+2;;;2*-1;
InChI key: FDMFQOCGNBYKPY-UHFFFAOYSA-N

Melting point: 1620°C
Density: 6.06 g/mL at 25 °C (lit.)
storage temp.: -20°C
solubility: Insoluble in H{2}O. Decomposes by hot HCl, HNO{3}
form: Powder
Specific Gravity: 6.062
color: white
biological source: rabbit
Water Solubility: insoluble H2O; decomposed by hot HCl, HNO3 [MER06]
Merck: 14,1712
Solubility Product Constant (Ksp): pKsp: 8.06

Compound Formula: CaO4W
Molecular Weight: 287.92
Appearance: solid
Melting Point: N/A
Boiling Point: N/A
Density: 6.06 g/cm3
Solubility in H2O: N/A
Exact Mass: 287.893182
Monoisotopic Mass: 287.893182

Molecular Weight: 287.92 g/mol
Hydrogen Bond Donor Count: 0
Hydrogen Bond Acceptor Count: 4
Rotatable Bond Count: 0
Exact Mass: 287.893183 Da
Monoisotopic Mass: 287.893183 Da
Topological Polar Surface Area: 80.3 Å²
Heavy Atom Count: 6
Complexity: 62.2
Isotope Atom Count: 0
Defined Atom Stereocenter Count: 0
Undefined Atom Stereocenter Count: 0
Defined Bond Stereocenter Count: 0
Undefined Bond Stereocenter Count: 0
Covalently-Bonded Unit Count: 2
Compound Is Canonicalized: Yes