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Conversion of Polycrystalline Alumina to Single‐Crystal Sapphire by Localized Codoping with Silica
Author(s) -
Thompson Gary S.,
Henderson Peter A.,
Harmer Martin P.,
Wei George C.,
Rhodes William H.
Publication year - 2004
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.2004.tb06334.x
Subject(s) - materials science , crystallite , sapphire , sintering , single crystal , crystal (programming language) , tube furnace , composite material , doping , mineralogy , optoelectronics , crystallography , optics , chemical engineering , metallurgy , laser , chemistry , programming language , physics , computer science , engineering
The effect of a localized SiO 2 codoping on the conversion of polycrystalline, MgO‐doped Al 2 O 3 tubes to single‐crystal sapphire was investigated. Codoping with SiO 2 before sintering intentionally triggered abnormal grain growth, which resulted in the full conversion of tube surfaces to single crystal without adversely affecting densification to a almost pore‐free, translucent state. The degree of surface conversion was strongly dependent on experimental variables, which included furnace temperature and codoping amount. Surface‐converted tubes had excellent physical properties, which included good thermal cycling resistance and optical properties superior to unconverted, polycrystalline Al 2 O 3 .