Diffraction studies of β″-magnesium sialon
| ISSN: |
1573-4803
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| Source: |
Springer Online Journal Archives 1860-2000
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| Topics: |
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
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| Notes: |
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”.
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| Type of Medium: |
Electronic Resource
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| URL: |