Formation of Uniform Crystalline Germanium(IV) Oxide Particles
Uniform polyhedral particles of crystalline germanium(IV) oxide with an average size of 2.0 μm and a relative standard deviation of 0.08 were prepared by cooling from 50 to 10 °C an ethanolic mixed solution (30% by volume) of 8.4 × 10-2nil dm-3 germanium (IV) and 1.7 mol dm-3 hydrochloric acid. The particles grew through a polynuclear layers mechanism as judged from chronomal analysis based on a fractional change of soluble germanium(IV) species remained in a supernatant solution. 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. An average size of the uniform particles thus obtained was estimated to be 3.4 µm with a relative standard deviation of 0.12. Additionally, uniform tetrahedral particles of sodium germanate(IV) (Na2Ge3O7 • 7H2O) were obtained at 100 °C and an initial pHi 8.5 from an ethanolic solution (50% by volume) of 3.5 × 10-2 mol dm-3 8-quinolinolatogermanium (IV) complex in the presence of a large amount of sodium ions.
KeywordsOxide Particle Molybdenum Blue Method Reaction Degree Chromium Hydroxide Polyhedral Particle
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