High-temperature infrared and dielectric properties of large sapphire crystal for seeker dome application
✍ Scribed by Guigen Wang; Mingfu Zhang; Jiecai Han; Xiaodong He; Hongbo Zuo; Xinhong Yang
- Publisher
- John Wiley and Sons
- Year
- 2008
- Tongue
- English
- Weight
- 259 KB
- Volume
- 43
- Category
- Article
- ISSN
- 0232-1300
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✦ Synopsis
Abstract
In this paper, large‐sized (∅︁230 mm × 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 (3 μm, 80–86%), essentially negligible dielectric loss (4.9×10^‐5^–3.7×10^‐4^), but fairly high dielectric constants (ε=9.4–12.5) in the temperature range of 30–1300°C. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)