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Electronic structure calculation of cohesive properties of some Si6−zAlzOzN8−z spinels

Lowther, J. E. and Schwarz, M. and Kroke, E. and Riedel, R. (2003):
Electronic structure calculation of cohesive properties of some Si6−zAlzOzN8−z spinels.
In: Journal of Solid State Chemistry, Elsevier, pp. 549-555, 176, (2), ISSN 00224596,
[Online-Edition: http://dx.doi.org/10.1016/S0022-4596(03)00327-X],
[Article]

Abstract

The structures of a spinel form of Si6−zAlzOzN8−z are investigated using techniques of ab initio density functional plane wave electronic structure theory with soft pseudopotentials. Four spinel configurations are considered corresponding to z=0, 1, 2, and 4. In the case of z=2 (Si2AlON3 spinels), that has now been synthesized, a normal or inversed configuration is considered. Very small energy differences are found suggesting that a mixed random atomic structure is very likely for the Si2AlON3 spinels. Results across the other range of spinels show that incompressible structures are associated with larger concentrations of N. These structures also have the larger cohesive energies. All spinels have direct energy band gaps varying between 3 and View the MathML source in the spinel 56-atom unit cell depending upon oxygen concentration.

Item Type: Article
Erschienen: 2003
Creators: Lowther, J. E. and Schwarz, M. and Kroke, E. and Riedel, R.
Title: Electronic structure calculation of cohesive properties of some Si6−zAlzOzN8−z spinels
Language: English
Abstract:

The structures of a spinel form of Si6−zAlzOzN8−z are investigated using techniques of ab initio density functional plane wave electronic structure theory with soft pseudopotentials. Four spinel configurations are considered corresponding to z=0, 1, 2, and 4. In the case of z=2 (Si2AlON3 spinels), that has now been synthesized, a normal or inversed configuration is considered. Very small energy differences are found suggesting that a mixed random atomic structure is very likely for the Si2AlON3 spinels. Results across the other range of spinels show that incompressible structures are associated with larger concentrations of N. These structures also have the larger cohesive energies. All spinels have direct energy band gaps varying between 3 and View the MathML source in the spinel 56-atom unit cell depending upon oxygen concentration.

Journal or Publication Title: Journal of Solid State Chemistry
Volume: 176
Number: 2
Publisher: Elsevier
Uncontrolled Keywords: Spinels, Oxides, Oxynitrides, Sialons, Electronic structure
Divisions: 11 Department of Materials and Earth Sciences > Material Science > Dispersive Solids
11 Department of Materials and Earth Sciences > Material Science
11 Department of Materials and Earth Sciences
Date Deposited: 25 Apr 2012 09:26
Official URL: http://dx.doi.org/10.1016/S0022-4596(03)00327-X
Identification Number: doi:10.1016/S0022-4596(03)00327-X
Funders: This work has, in part, been funded through a German-NRF(South Africa) cooperative project (BMBF-NRF Project WTZ39.6.L1A.6.F). We are further grateful for support by the Deutsche Forschungsgemeinschaft (Bonn, Germany), and DeBeers Industrial Diamond Division (Johannesburg, South Africa).
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