Germanate

Germanates are compounds of germanium, which are derived from its oxide. In almost all germanium-containing minerals, the germanium is present as germanate.

Since the properties of germanium are similar to those of silicon, outweighs the acidic character of the germanium dioxide ( GeO2 ). Therefore latter reacts with alkaline solutions to the germanates. Further germanates are obtained by the reaction of germanium with various metal oxides when melted together.

Classification

There are Germanates different composition are known ( M: singly charged metal cation, X: halide):

• Orthogermanate, M4GeO4
• Metagermanate, ( M2GeO3 ) n
• Meta - digermanate, ( M2Ge2O5 ) n
• Hexahydroxogermanate, M2Ge (OH) 6
• Hexahalogenogermanate, M2GeX6

Metagermanate and meta- digermanate are present in polymeric form. The germanates the underlying germanium acids are similar to the carbon dioxide and the silicon-oxygen acids in anhydrous form is not stable, but only in dilute solutions. By, for example, the Halogenogermanaten Kaliumhexafluorogermanat ( K2GeF6 ) is known which may be obtained from potassium fluoride and germanium tetrafluoride.

Substance class

Germanates are a class of substances with very diverse properties. Between the oxygen compounds of germanium and the corresponding silicon compounds, many analogies can be observed. Silicate and germanate are often isotypic. From the germanium one also knows zeolitic structures and the tendency to glass formation. Due to their high refractive index, they are occasionally used for optical elements, as used for example for wide-angle lenses in photography. Many doped germanate show luminescence when irradiated with UV light: (Sr, Ba) 2 (Mg, Zn) Ge2O7: Pb ( blue-violet ), Zn2GeO4: Mn ( green ), MgGeO3: Mn (Deep Red ).

Admixtures of lead germanate in ceramics generate a material having semiconducting properties.

Sodium and Ammoniumgermanate can be used as catalysts in the polyester synthesis.

Bismuth germanate is used in scintillation counters.