High-temperature infrared and dielectric properties of large sapphire crystal for seeker dome application by Guigen Wang, Mingfu Zhang, Jiecai Han, Xiaodong He, Hongbo Zuo, and Xinhong Yang

Crystal Research and Technology

Cryst. Res. Technol. 43, 531 (2008) - Abstract -

High-temperature infrared and dielectric properties of large sapphire crystal for seeker dome application

Guigen Wang, Mingfu Zhang, Jiecai Han, Xiaodong He, Hongbo Zuo, and Xinhong Yang

Center for Composite Materials, Harbin Institute of Technology, Harbin 150080, P. R. China

Keywords	sapphire, infrared transmission, dielectric properties, high temperature, SAPMAC method
PACS	81.40.Tv, 78.20.Ci, 42.70.Km
DOI	10.1002/crat.200711066

In this paper, large-sized (230 mm diameter x 210 mm, 27.5 kg) sapphire was successfully grown by SAPMAC (sapphire growth technique with micro-pulling and shoulder-expanding at cooled center) method; and hemisphere dome (140 mm diameter, 5 mm thickness) was fabricated from as-grown boule. Also, its high temperature infrared transmission (2-7 μm, 20–800°C) and microwave dielectric properties (8–16.5 GHz, 30–1300°C) were investigated. The experimental results show that sapphire crystal exhibits high infrared transmittance, essentially negligible dielectric loss, but fairly high dielectric constants in the temperature range of 30–1300°C.

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