Monodispersed crystalline hexagonal germanium (IV) oxide particles with an average size of 2.0, μm were prepared by cooling from 50 to 10°C an ethanolic mixed solution (30% by volume) of 8.4 x 10
-2 mol dm
-3 germanium (IV) and 1.7 mol dm
-3 hydrochloric acid, for example. A fraction of soluble germanium (IV) species in a supernatant solution finally reached 0.36 at 10°C after 325h. A rate-determining step of the particle growth was revealed to be a polynuclear layers mechanism as judged from the fractional change of the germanium (IV) species. Uniform cuboidal particles of crystalline germanium (IV) oxide were also prepared by oxidizing at 100°C a mixed solution of 0.11 mol dm
-3 tris (oxalato) germanate (IV) complex, 4.0 mol dm
-3 sulfuric acid, and ethanol of 13% by volume with 2.2 mol dm
-3 hydrogen peroxide.
Additionally, uniform tetrahedral particles of Na
2Ge
3O, ? 7H
2O were obtained at 100°C and pHi 8.5 from an ethanolic solution (50% by volume) of 3.5 x 10
-2 mol dm
-3 8-quinolinolatogermanium (IV) complex in the presence of sodium ions.
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