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Journal of Materials Science

, Volume 19, Issue 5, pp 1726–1736 | Cite as

Diffraction studies of β″-magnesium sialon

  • G. Leng-Ward
  • M. H. Lewis
  • S. Wild
Papers

Abstract

The compositions of high magnesium content β″-magnesium sialon crystals within the 3M/4X plane of the Mg-Si-Al-O-N system indicate some form of metal atom ordering wihtin the β″ structure. Although it is not possible using X-ray diffraction to detect weak additional reflections arising from the ordering between magnesium, aluminium, and silicon atoms, such weak reflections are revealed on electron diffraction photographs for a β″ phase, resulting in a tripling of the hexagonal latticec-dimension. These show β″ to have a structure very similar to rhombohedral willemite (Zn2SiO4), with the (Mg, Al) metal atoms ordered with respect to the silicon atoms in a 2∶1 ratio. However, there are some additional weak diffraction spots with indices not obeying the rhombohedral condition of −h+k+l=3n. It is proposed that the structure of this β″ is identical to that of willemite and the extra spots are a result of some form of twinning, which implies the existence of “ordered microdomains”.

Keywords

Magnesium Hexagonal Electron Diffraction Metal Atom Diffraction Study 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Chapman and Hall Ltd. 1984

Authors and Affiliations

  • G. Leng-Ward
    • 1
  • M. H. Lewis
    • 2
  • S. Wild
    • 3
  1. 1.Department of SciencePolytechnic of WalesPontypriddUK
  2. 2.Department of PhysicsUniversity of WarwickCoventryUK
  3. 3.Department of Civil Engineering and BuildingPolytechnic of WalesPontypriddUK

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