# Crystallography question

Discussion in 'Physics' started by boks, Mar 11, 2009.

1. ### boks Thread Starter Active Member

Oct 10, 2008
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0
According to my handbook, rutile ($TiO_2$) has a primitive tetragonal cell consisting of 6 atoms. How is that possible when each lattice point contains 1/8 atom or molecule?

Apr 20, 2004
15,815
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3. ### studiot AAC Fanatic!

Nov 9, 2007
5,005
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The rutile structure is not close packed. It shows 6:3 coordination which means that each titanium atom is surrounded by 6 (not 8) oxygen atoms arranged at the vertices of an octahedron.

An octahedon has 8 faces but only 6 vertices

Each oxygen is coordinated to 3 titaniums in a planar equilateral triangle.