The structures of the four metal dioxides GeO2, SnO2, RuO2 and IrO2 (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 P42/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.

No abstract

Neutron powder diffraction data for Moo2 [P21/c, a 5.6102(3), b 4.8573(2), c 5.6265(3) A, / 3 120.915(2)0] and WOz [P21/c, a 5.5769(2), b 4.8986(1), c 5.6644(2) A, , B 120.678(1)0] have been employed t o refine structural parameters by the Rietveld method. The results confirm previous studies but have considerably greater precision.

No abstract