why tetragonal unit cells does not form fcc,bcc,end centred.

Asked by lokesh WARAN | 12th Feb, 2014, 07:04: AM

Expert Answer:

Dear lokesh

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However the following answer might clear your doubt.

In crystallography, the tetragonal crystal system is one of the 7 lattice point groups. Tetragonal crystal lattices result from stretching a cubic lattice along one of its lattice vectors, so that the cube becomes a rectangular prism with a square base (a by a) and height (c, which is different from a).

There are two tetragonal crystal structure types. Bravais lattices: the simple tetragonal (from stretching the simple-cubic lattice) and the centered tetragonal (from stretching either the face-centered or the body-centered cubic lattice). One might suppose stretching face-centered cubic would result in face-centered tetragonal, but face-centered tetragonal is equivalent to body-centered tetragonal, BCT (with a smaller lattice spacing). BCT is considered more fundamental, so that is the standard terminology.

 
 
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Answered by  | 14th Feb, 2014, 10:59: AM

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