Ceramic Metal Oxides. Artistic materials are inorganic, non-metallic materials produced using mixes of a metal and a non metal. Artistic materials may be crystalline or halfway crystalline. They are shaped by the activity of warmth and consequent cooling.
Transition-metal oxide ceramics from II to IV, such as TiO2, ZnO, NiO, Fe2O3, SnO2, and others, exhibit semiconductor properties, and are used mainly for the applications of gas sensors, solar energy, and in the electronics industry. A semiconductor ceramic is a material that has electrical conductivity between that of a metal and an insulator. The conductivity of the semiconductor is tunable by doping with different types of anions and cations. For example, SnO2 and hematite (Fe2O3) were found be to potential materials for a gas sensor application. Although pure hematite or tin oxide exhibited poor conductive properties, Si-doped hematite or F-doped SnO2 exhibited very good conductivity due to an increase in the charge carrier density of the material. In solar energy, a band gap (the energy gap between conduction and valance band) of semiconductor oxide ceramic material is a very important property. The type of semiconductor (n-type or p-type), the conductive property, and the band-gap property are mainly influenced by the type and amount of doping. The selection of the band gap depends on the application. Ideally, for solar energy a lower band-gap oxide ceramic is required, which could absorb a larger amount of light from the solar spectrum. For example, the n-type semiconductor titanium dioxide (TiO2) has been a prime candidate for photoelectrodes in the application of a photoelectrochemical cell using solar energy due to its stability, nontoxicity, and relatively low cost. However, the band-gap size of the TiO2 photocatalyst is ∼3.2 eV, which indicates that it only absorbs a small UV fraction of solar light (about 3–4%) which can be utilized to induce electronic photoexcitation into the conduction band with the creation of holes in the valence band (10,57). This leads to its relatively low photoactivity as an electrode. Doping the TiO2 lattice with various metals and nonmetals is a potential way to improve the photoactivity of TiO2 in the visible region through reduction of the band edge. The semiconductor nature of ceramic materials can be mainly assessed by their conductivity, band gap, and light absorption properties