Sapphire Ceramic - Material Information

Synthetic sapphire is a single-crystal form of aluminum oxide (Al₂O₃) valued for its exceptional thermal, optical, and mechanical performance. It offers a combination of high hardness, excellent electrical insulation, and superior thermal conductivity, making it indispensable in optics, electronics, and precision engineering. With a wide optical transmission range from 0.2 to 5.5 µm, sapphire is widely used in infrared and ultraviolet optical components.

Material Overview

Sapphire’s hexagonal corundum crystal structure provides exceptional hardness (Mohs 9), second only to diamond, and high compressive strength exceeding 2000 MPa. It has a melting point near 2040 °C, thermal conductivity of 35–46 W·m⁻¹·K⁻¹ (at 298 K), and a dielectric strength of 13–15 MV·m?¹. The optical anisotropy of sapphire—expressed in its distinct ordinary and extraordinary refractive indices (n_o ? 1.76, n_e ? 1.77)—affects polarization and birefringence behavior across visible and infrared wavelengths (Kaplan & Thomas, 2002). Hydrogen content and growth technique strongly influence optical uniformity; low-hydrogen Verneuil-grown crystals display enhanced transmission and reduced absorption (Mogilevsky et al., 2008). Sapphire also maintains high volume resistivity (~10¹⁴ ?·cm) and low thermal expansion (5.0×10?? K?¹), ensuring dimensional stability under extreme conditions.

Applications and Advantages

Sapphire is used extensively in high-performance optical windows, watch crystals, laser systems, and high-vacuum viewports. Its resistance to abrasion, radiation, and thermal shock enables reliable performance in semiconductor and aerospace applications. Single-crystal sapphire fibers have been demonstrated as optical waveguides capable of transmitting up to 600 mJ of laser energy with minimal attenuation (Merberg & Harrington, 1993). Due to its high chemical stability and broad transmission window, sapphire also finds use in high-pressure lamps, infrared sensors, and substrate materials for GaN-based LEDs and RF electronics. These qualities make sapphire one of the most versatile advanced ceramics for high-stress optical and thermal applications.

Goodfellow Availability

Goodfellow offers high-purity synthetic sapphire (Al₂O₃ 99.9%) in various geometries, including single-crystal components and precision-machined parts. These materials provide excellent optical, mechanical, and electrical properties suited for demanding research and industrial environments. Explore sapphire and other advanced ceramics through the Goodfellow product finder.

References

• Kaplan, S. G., & Thomas, M. E. (2002). Measurement of the O-ray and E-ray infrared refractive index and absorption coefficients of sapphire from 10 K to 295 K. Proceedings of SPIE. https://scispace.com/papers/measurement-of-the-o-ray-and-e-ray-infrared-refractive-index-3zimrxnxp9
• Mogilevsky, R., Sharafutdinova, L. G., & Mittl, S. D. (2008). Optical properties of sapphire. Proceedings of SPIE. https://scispace.com/papers/optical-properties-of-sapphire-lmfjdbxttw
• Merberg, G. N., & Harrington, J. A. (1993). Optical and mechanical properties of single-crystal sapphire optical fibers. Applied Optics, 32(18), 3201–3206. https://scispace.com/papers/optical-and-mechanical-properties-of-single-crystal-sapphire-7lhhta22hp
• Hu, Z., Feng, Q., Zhang, J., Li, F., Li, X., Feng, Z., Zhang, C., & Hao, Y. (2017). Optical properties of (AlxGa1?x)₂O₃ on sapphire. Superlattices and Microstructures, 113, 451–458. https://scispace.com/papers/optical-properties-of-al-x-ga-1-x-2-o-3-on-sapphire-4rap2t7gf2