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High‐Temperature Hydroxylation of Mullite
Author(s) -
Rüscher Claus H.,
Shimada Shiro,
Schneider Hartmut
Publication year - 2002
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.1151-2916.2002.tb00322.x
Subject(s) - infrared spectroscopy , mullite , chemistry , spectroscopy , single crystal , crystallography , infrared , absorption (acoustics) , crystal (programming language) , analytical chemistry (journal) , absorption spectroscopy , materials science , optics , ceramic , programming language , physics , organic chemistry , chromatography , quantum mechanics , computer science , composite material
A plane‐parallel, polished, 0.9 mm thick, single‐crystal (001) plate of 2:1 mullite was treated for 6 h at 1600°C in an Ar/H 2 O (90/10) gas mixture at 100 kPa. Optical microscopy studies and infrared (IR) reflection spectroscopy studies of the lattice vibrations yielded no evidence for change with respect to the untreated reference crystal. However, IR absorption spectroscopy showed that structurally bound OH groups were formed by the heat treatment in the Ar/H 2 O gas mixture. IR absorption depth profile analysis showed a rather homogeneous OH distribution through the crystal. Five different hydroxyl groups were separated according to dipole orientations and peak positions: E ‖ a , ω a 1 = 3447 cm −1 , ω a 2 = 3579 cm −1 ; E ‖ b , ω b 1 = 3456 cm −1 , ω b 2 = 3544 cm −1 ; and E ‖ c , ω c 1 = 3498 cm −1 . All IR peaks were strongly broadened (between 90 and 150 cm −1 ) because of a distribution in O‐H binding distances caused by the real structure of mullite.