High-pressure silica polymorphs as hardest known oxides

We report the results of an experimental study of the silica phases (stishovite and SiO 2 with α-PbO 2 like structure). These phases were synthesized in laser- and externally electrically heated Mao–Bell type diamond anvil cells (DACs) from α-cristobalite as a starting material at pressures above 80...

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Bibliographic Details
Published in:Materials chemistry and physics 2001-02, Vol.68 (1), p.77-79
Main Authors: Dubrovinskaia, N.A, Dubrovinsky, L.S
Format: Article
Language:English
Subjects:
Condensed matter: structure, mechanical and thermal properties
Diamond anvil cells
Elasticity, elastic constants
Exact sciences and technology
Hardness
High pressure
Mechanical and acoustical properties of condensed matter
Mechanical properties of solids
Physics
Silica
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Summary:We report the results of an experimental study of the silica phases (stishovite and SiO 2 with α-PbO 2 like structure). These phases were synthesized in laser- and externally electrically heated Mao–Bell type diamond anvil cells (DACs) from α-cristobalite as a starting material at pressures above 80 GPa and temperatures above 1200 K. We measured the hardness ( H) of both phases and found that the value for the α-PbO 2-like silica, H=31±3 GPa, is very close to that of stishovite, H=32±2 GPa, for polycrystalline material obtained in electrically heated DACs. Thus, these two polycrystalline silica phases are hardest known oxides and representatives of hardest known polycrystalline materials in general.
ISSN:0254-0584
1879-3312
DOI:10.1016/S0254-0584(00)00284-4