Titanium dioxide is hard and transparent. The solubility is smaller than 0.001 g/100 g H2O (298 K). It is soluble in concentrated sulfate acid. It can be used as a transparent electrode for the wavelength region and materials (in relation with temperature) that SnO2 cannot be used.

Crystal System

The space lattice of TiO2 belongs to the tetragonal system, and its rutile-type structure has lattice constants of a=0.459373 nm and c=0.295812 nm (25℃).

Production 

It produces naturally and it is called rutile or titania. Vacuum evaporation is carried out by direct heating of a W boat. Transparent conductive thin films of TiO2 are fabricated using the following methods: 

Evaporated Ti films are disposed to air to make oxide and some treatment is done to stop oxidation at the proper conductivity. 

Evaporated TiO2 films are oxidized in the activated oxygen. 

Evaporated Ti thin films are oxidized actively within oxygen glow discharge at low vacuum. The application to any wavelength is possible by choosing an appropriate substrate.