What is the difference between fused silica and quartz?
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Difference Between Fused Silica and Quartz
Fused silica and quartz are both forms of silicon dioxide (SiO2), but they differ in terms of their purity, structure, and production methods, which result in distinct physical and optical properties.
Purity
Fused Silica: Extremely high purity with minimal inclusions or bubbles. It is synthesized from high-purity silicon compounds and does not contain crystalline structures.
Quartz: Naturally occurring and can contain various levels of impurities and inclusions, depending on the source. It has a crystalline structure.
Structure
Fused Silica: Amorphous (non-crystalline) structure due to the manufacturing process, which involves the melting and rapid cooling of silicon dioxide.
Quartz: Crystalline structure, which is its natural state, with a regular and repeating pattern of silicon and oxygen atoms.
Production Methods
Fused Silica: Produced through a synthetic process by melting high purity silica in a flame or using chemical vapor deposition.
Quartz: Mined from natural deposits and then cut, ground, and polished to the desired shape and finish.
Physical and Optical Properties
Fused Silica: Exhibits excellent optical clarity, high resistance to thermal shock, and low coefficient of thermal expansion. It is often used in high-precision optical applications.
Quartz: Also has good optical properties but is less resistant to thermal shock compared to fused silica. It is used in applications where its crystalline properties are advantageous.
Applications
Both materials are used in a variety of optical applications, but fused silica is preferred for more demanding environments, such as in semiconductor manufacturing, UV transmission, and high-power laser systems. Quartz is often used in lenses, prisms, and other optical components where extreme purity and thermal resistance are not as critical.
In summary, while both fused silica and quartz are forms of silicon dioxide, their differences in purity, structure, and production methods lead to distinct properties and applications in the field of optical engineering.