Fused quartz
A high-purity glass used in optics, semiconductors, and high-temperature applications.
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Fused quartz is a glassy, non-crystalline material made by melting high-purity silica sand that consists of quartz crystals.[1] Despite being composed of the same material, fused quartz in its glassy state exhibits physical characteristics that are quite distinct from those of crystalline quartz.[2] Although the names fused quartz and fused silica are often used synonymously, they may indicate distinct production methods that lead to varying levels of trace impurities.[2]
Quick Facts
- Common impurities
- Aluminium
- titanium
- and hydroxyl (OH) groups
- Key properties
- High strength
- chemical resistance
- low thermal expansion
- wide UV-to-IR transparency
Facts from the source article.
Key facts and history
Because of its physical strength, fused quartz was used in deep diving vessels and in windows of crewed spacecraft.[3] In the semiconductor industry, its combination of strength, thermal stability, and UV transparency makes it an excellent substrate for projection masks for photolithography.[4] Its UV transparency also finds use as windows on EPROMs, which are erased by exposure to strong ultraviolet light.[4] While fused quartz is typically clear, it may become semi-transparent if tiny air pockets become enclosed inside it.[5]
The melting process occurs at around 2200 °C, achieved through either an electric furnace or one fueled by a gas and oxygen mixture.[6] Commercial silica glass comes in four fundamental types, each made by a distinct process: Type I from electrically melted natural quartz, Type II from flame-fused quartz powder, Type III from burning silicon tetrachloride in a hydrogen-oxygen flame, and Type IV from burning silicon tetrachloride in a plasma flame free of water vapor.[1] Aluminum and titanium are the main impurities, and they influence how well the material transmits ultraviolet light.[7] The amount of water in fused quartz depends on how it is made; material fused with a flame has a higher concentration of hydroxyl groups.[5]
For infrared-grade material, the hydroxyl content is usually less than 10 parts per million.[5]
What the research sources say
The Swift Glass account states that quartz glass is created from grains of natural material that are melted and purified, retaining some residual impurities from raw material.[8] The same source notes that fused silica is an entirely synthetic material and is technically the purest glass.[8] According to the Swift Glass account, fused silica has superior ultraviolet performance to natural quartz and is ideal for UV transmitting optics.[8] The CPU History account explains that EPROMs are packaged in a ceramic package because of the embedded quartz crystal, as ceramic and quartz expand and contract at the same rate.[9]
References
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: Kitamura, "Optical Constants of Silica Glass From Extreme Ultraviolet to Far Infrared at Near Room Temperatures", Applied Optics, 2007-11-19, p. 8118–8133 (original not read by us) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: "Quartz vs. Fused Silica: What's the Difference?", Swift Glass, 2015-09-08 (we also read that source) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: Salem, "Transparent Armor Ceramics as Spacecraft Windows", Journal of the American Ceramic Society, 2012; Evaluation of Siliceous Cored Armor for the XM60 Tank (original not read by us) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: "Intel 1702A 2K (256 x 8) UV Erasable PROM"; "CPU History - EPROMs", www.cpushack.com (we also read that source) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: "Fused quartz - Acemap", ddescholar.acemap.info (original not read by us) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: Varshneya, "Fundamentals of inorganic glasses", Elsevier S & T, 2019 (we also read that source) en.wikipedia.org
- Wikipedia, "Fused quartz" (CC BY-SA 4.0), which cites: Chemical purity of fused quartz / fused silica, www.heraeus-quarzglas.com (original not read by us) en.wikipedia.org
- "Quartz vs. Fused Silica: What's the Difference?", Swift Glass, 2015-09-08. facts only, no text reused. swiftglass.com
- "CPU History - EPROMs", www.cpushack.com. facts only, no text reused. cpushack.com
Each numbered sentence above was checked against the source it cites before publication. Sentences citing Wikipedia adapt text from the English Wikipedia article Fused quartz (contributors), used under CC BY-SA 4.0; this entry is available under the same licence. Other sources were used for facts only; no text or images are copied from them.
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Sources
Compiled from Wikipedia and the sources listed below. Text from Wikipedia is available under CC BY-SA 4.0; this entry is adapted from it.
- Wikipedia: Fused quartz (CC BY-SA 4.0).
- Word definitions: the , each quoted from its Wikipedia article.
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