Germanium dioxide

Germanium

White odorless solid

Fixed

4.23 g · cm -3

1086-1115 ° C

Poorly in water ( 4.5 g · l-1 at 25 ° C)

1.7

Attention

1250 mg · kg -1 ( LD50, rat, oral)

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Germanium ( IV) oxide is a chemical compound selected from the group consisting of germanium compounds, and oxides.

Occurrence

Germanium (IV ) oxide occurs naturally as the mineral Argutit.

Production and representation

Germanium ( IV) oxide is formed when strong annealing of germanium or germanium in an oxygen atmosphere.

Very simple is the hydrolysis of germanium (IV ) chloride.

Properties

Germanium ( IV) oxide is in a plurality of crystal structures before parallel to those of silica. Hexagonal GeO2 (melting point 1115 ° C, density 4.7 g / cm ³) with the same structure as α - quartz and formed in the hydrolysis of germanium chloride and the decomposition of germanates. Tetragonal GeO2 (as mineral Argutit, melting point 1086 ° C, density 6.239 g / cm ³ ) having a rutile -like structure ( such as Stishovite ) and is produced by heating for several hours of germanium ( IV) oxide with water under pressure and at higher temperatures, or in a evaporation of an aqueous germanium ( IV) oxide solution with a little ammonium fluoride. The amorphous silica glass corresponding to GeO2 (density 3.637 g / cc ) and still occurs during cooling of a melt of germanium ( IV) oxide. The rutile modification can be placed at 1033 ° C in the soluble quartz analog form. This modification is in contrast to the other slightly soluble in water, the solution distinctly acid reacts (formation of germanium acid). In contrast, germanium acids triggers (IV ) oxide is difficult ( in strong hydrochloric acid slightly ) in alkaline solutions (eg, lye ) slightly, with Germanates arise.

Use

Germanium ( IV) oxide is used for the production of transparent in the infrared optical lenses. In polyester chemistry, it is used as a catalyst in the preparation of certain non-yellowing polyester fibers and granules are used, especially for recyclable PET bottles. It also serves as starting material for the preparation of such Hafniumgermanat HfGeO4 germanates.