Германия диоксид

Описание

Germanium oxide also called Germanium dioxide is the oxide of germanium, an inorganic compound, featuring the chemical formula GeO₂. It is formed as a passivation layer on pure germanium after exposure to oxygen. Germanium dioxide generally has a low toxicity, but shows severe nephrotoxicity at higher doses. Germanium dioxide is still offered on the market in some questionable miracle therapies. Exposure to high doses of germanium dioxide can lead to germanium poisoning.

Химические свойства

White powder, hexagonal, tetragonal, and amorphous.

Использование

Germanium oxide can be used in Phosphors, transistors and diodes, infraredtransmitting glass.

Профиль безопасности

Poison by intraperitoneal route. When heated to decomposition it emits acrid smoke and irritating fumes.

Методы очистки

The oxide (GeO2) is usually prepared by hydrolysing redistilled GeCl4 and igniting it in order to remove H2O and chloride. It can be further purified by dissolving in hot H2O (solubility is 4g/L cold) evaporating and drying the residual crystalline solid. When the soluble form (which is produced in H2O at 355o) is heated for 100hours, it is converted to the insoluble form. This form is stable at temperatures up to 1033o, and fusion at 1080o for 4hours causes complete de-vitrification and it reverts to the soluble form. [Müller & Blank J Am Chem Soc 46 2358 1924, Dennis & Laubengayer J Am Chem Soc 47 1945 1925, Laubengayer & Morton J Am Chem Soc 54 2303 1932, Schenk in Handbook of Preparative Inorganic Chemistry (Ed. Brauer) Academic Press Vol I p 706 1963.]

Структура и конформация

Germanium oxide ccurs in two crystalline and one amorphous modifications: (1) a tetragonal rutile form, refractive index 2.05, density 6.24 g/cm3 at 20°C. (2) white hexagonal quartz modification, refractive index 1.735, density 4.70 g/cm3 at 18°C, and (3) a glassy amorphous form, refractive index 1.607, density 3.64 g/cm3 at 20°C. The tetragonal form is practically insoluble in water, while the hexagonal and the amorphous modifications have low solubilities; 0.45 and 0.52% respectively, at 25°C. Aqueous solutions are acidic due to formation of metagermanic acid, H2GeO3. Hexagonal modification converts to a tetragonal crystal system when heated at 350°C in water under pressure. Both crystalline forms convert to a glass-like amorphous GeO2 when heated at 1,100°C.