Rutile 6: the equivalence of the octahedral sites in rutile

It is easiest to interpret the structure to the left from the direction in which it first loads up on the screen. It shows eight rutile unit cells and demonstrates, using the central titanium ion, how the corner positions of the unit cell are also in contact with six neighbouring oxide ions. The violet wireframe around the central titanium ion shows that it is in a similar (distorted) octahedral environment to the titanium ions at the body-centre of the unit cells. Note that the central violet octahedron is sharing each of its corners with a neighbouring (blue) octahedron, while the blue octahedra are sharing edges with their blue neighbours. The principal axis of the blue and violet octahedra are pointing at right angles to each other, but the axes of neighbouring perpendicular octahedra are separated by half a unit cell length along the principal axis of the cell (ie the axis carrying the tetragonal distortion). All the axes of the octahedra are pointing in the direction of the diagonal of the square face of the unit cell.

Are the titanium ions at the corner positions in entirely equivalent positions to the body-centre ions?

Go to page 7 to consider an equivalent rutile unit cell.

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