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Synthesis of cubic silicon nitride

Riedel, Ralf and Zerr, Andreas and Miehe, Gerhard and Serghiou, George and Schwarz, Marcus and Kroke, Edwin and Fueß, Hartmut and Kroll, Peter and Boehler, Reinhard (1999):
Synthesis of cubic silicon nitride.
In: Nature, NPG, pp. 340-342, 400, (6742), ISSN 00280836,
[Online-Edition: http://dx.doi.org/10.1038/22493],
[Article]

Abstract

Silicon nitride (Si3N4) is used in a variety of important technological applications. The high fracture toughness, hardness and wear resistance of Si3N4-based ceramics are exploited in cutting tools and anti-friction bearings1; in electronic applications, Si3N4 is used as an insulating, masking and passivating material2. Two polymorphs of silicon nitride are known, both of hexagonal structure: alpha- and beta-Si3N4. Here we report the synthesis of a third polymorph of silicon nitride, which has a cubic spinel structure. This new phase, c-Si3N4, is formed at pressures above 15 GPa and temperatures exceeding 2,000 K, yet persists metastably in air at ambient pressure to at least 700 K. First-principles calculations of the properties of this phase suggest that the hardness of c-Si3N4 should be comparable to that of the hardest known oxide (stishovite3, a high-pressure phase of SiO2), and significantly greater than the hardness of the two hexagonal polymorphs.

Item Type: Article
Erschienen: 1999
Creators: Riedel, Ralf and Zerr, Andreas and Miehe, Gerhard and Serghiou, George and Schwarz, Marcus and Kroke, Edwin and Fueß, Hartmut and Kroll, Peter and Boehler, Reinhard
Title: Synthesis of cubic silicon nitride
Language: English
Abstract:

Silicon nitride (Si3N4) is used in a variety of important technological applications. The high fracture toughness, hardness and wear resistance of Si3N4-based ceramics are exploited in cutting tools and anti-friction bearings1; in electronic applications, Si3N4 is used as an insulating, masking and passivating material2. Two polymorphs of silicon nitride are known, both of hexagonal structure: alpha- and beta-Si3N4. Here we report the synthesis of a third polymorph of silicon nitride, which has a cubic spinel structure. This new phase, c-Si3N4, is formed at pressures above 15 GPa and temperatures exceeding 2,000 K, yet persists metastably in air at ambient pressure to at least 700 K. First-principles calculations of the properties of this phase suggest that the hardness of c-Si3N4 should be comparable to that of the hardest known oxide (stishovite3, a high-pressure phase of SiO2), and significantly greater than the hardness of the two hexagonal polymorphs.

Journal or Publication Title: Nature
Volume: 400
Number: 6742
Publisher: NPG
Divisions: 11 Department of Materials and Earth Sciences
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science > Structure Research
Date Deposited: 08 Jun 2012 06:57
Official URL: http://dx.doi.org/10.1038/22493
Identification Number: doi:10.1038/22493
Funders: This work was supported by the Deutsche Forschungsgemeinschaft, Bonn, Germany, and the Fonds der Chemischen Industrie, Frankfurt, Germany.
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