Quartz Glass vs Sapphire Glass: Technical Comparison, Performance Analysis, and Material Selection Guide

Although quartz and sapphire are both transparent and colorless glass and look very similar, they differ fundamentally in their physical properties, optical properties, and practical applications. This article will systematically compare quartz glass and sapphire glass from several key dimensions.

Material Composition

Quartz glass is an amorphous material with consistent properties in all directions; sapphire glass is a synthetic single-crystal alumina, with significant differences in properties across different crystal orientations.

Item	Quartz Glass	Sapphire Glass
Chemical Composition	SiO₂ (≥99.99%)	Al₂O₃ (Single Crystal)
Structure	Amorphous	Single Crystal
Isotropy	Yes	No (Anisotropic)

Hardness & Mechanical Properties

Sapphire glass has a higher hardness and is not easily scratched, making it suitable for wear-resistant applications, while quartz glass has a greater advantage in impact resistance.

Property	Quartz Glass	Sapphire Glass
Mohs Hardness	6–7	9
Scratch Resistance	Moderate	Extremely High
Impact Resistance	Good	High strength but brittle

Optical Properties

Quartz glass is the material of choice for ultraviolet optics and laser systems; sapphire glass is suitable for high-strength optical windows.

Parameter	Quartz Glass	Sapphire Glass
Transmission Range	185 nm – 2500 nm	150 nm – 5500 nm
UV Transmittance	Excellent	Good
Refractive Index	~1.46	~1.76
Birefringence	None	Present

Thermal Properties

Quartz glass significantly outperforms sapphire in rapid temperature cycling Ideal for vacuum systems, UHV chambers, and high-temperature optical components

Item	Quartz Glass	Sapphire Glass
Softening Point	~1730 °C	>2000 °C
Thermal Expansion Coefficient	Very Low	Low
Thermal Shock Resistance	Excellent	Moderate

Typical Application Scenarios

When Quartz Glass Is the Better Choice

Semiconductor process windows
Vacuum and UHV chamber viewports
UV and laser optical components
Medical and analytical instruments

When Sapphire Glass Is the Better Choice

High-wear protective windows
High-pressure or corrosive environments
Aerospace and defense systems
High-end optical and sensor protection components

Conclusion

For applications requiring precision machining of quartz glass or sapphire glass, working with an experienced advanced ceramics and optical materials manufacturer is essential to ensure quality, performance, and consistency.

Jundro Ceramics is an excellent manufacturer of quartz/sapphire machining, which can provide you with material selection, drawing evaluation or application selection advice, and further optimize the design and cost according to the specific use environment.