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Merck

Hafnium Germanate from a Hydrous Hafnium Germanium Oxide Gel.

Inorganic chemistry (2001-10-24)
P. M. Lambert
RESUMO

The gel chemistry of germanium is explored through the formation and composition of a hydrous metal oxide precursor gel used in the preparation of the HfGeO(4) and HfGeO(4):Ti X-ray phosphors. The enhanced solubility of hexagonal GeO(2) in dilute ammoniacal solutions is exploited to give a convenient and high-yield precipitation. The precursor gel is shown by FT-IR to be a diphasic mixture of hydrous hafnia and an ammonium germanate gel. Thermal treatment drives the crystallization of a hafnium-rich, simple tetragonal Hf(1)(-)(x)()Ge(x)()O(2) structure at 893 degrees C, that upon further heating to 1200 degrees C yields scheelite HfGeO(4).

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Sigma-Aldrich
Germanium(IV) oxide, (crystalline powder), 99.998% trace metals basis
Sigma-Aldrich
Hafnium(IV) oxychloride hydrate, 99.99% trace metals basis (purity excludes zirconium)