Structural Studies of Rutile-Type Metal Dioxides

The structures of the four metal dioxides GeO 2 , SnO 2 , RuO 2 and IrO 2 (germanium, tin, ruthenium and iridium dioxides, respectively) have been redetermined by Rietveld refinement from neutron diffraction powder data. The four dioxides all adopt the rutile-type structure, space group P 42/ mnm (no. 136), with a = 4.4066 (1), 4.7374 (1), 4.4968 (2) and 4.5051 (3), c = 2.8619 (1), 3.1864 (1), 3.1049 (1) and 3.1586 (2) Å, and x = 0.3060 (1), 0.3056 (1), 0.3053 (1) and 0.3077 (3), respectively. These results are compared with those for other metal dioxides that adopt the rutile structure and trends in structural and thermal vibrations for a series of 11 metal dioxides which adopt the rutile-type structure are described.