Type or paste a DOI name into the text box. Follow the link for more nanostructures and nanomaterials synthesis properties and applications pdf. S61: Avoid release to the environment. Zinc oxide is an inorganic compound with the formula ZnO.
ZnO is a wide-bandgap semiconductor of the II-VI semiconductor group. The native doping of the semiconductor due to oxygen vacancies or zinc interstitials is n-type. Pure ZnO is a white powder, but in nature it occurs as the rare mineral zincite, which usually contains manganese and other impurities that confer a yellow to red color. Crystalline zinc oxide is thermochromic, changing from white to yellow when heated in air and reverting to white on cooling. Zinc oxide is an amphoteric oxide. C with a standard oxygen pressure.
It reacts with hydrogen sulfide to give zinc sulfide. Zinc oxide crystallizes in two main forms, hexagonal wurtzite and cubic zincblende. This and other lattice symmetry properties result in piezoelectricity of the hexagonal and zincblende ZnO, and pyroelectricity of hexagonal ZnO. ZnO is a relatively soft material with approximate hardness of 4. Its elastic constants are smaller than those of relevant III-V semiconductors, such as GaN. Among the tetrahedrally bonded semiconductors, it has been stated that ZnO has the highest piezoelectric tensor, or at least one comparable to that of GaN and AlN.
Advantages associated with a large band gap include higher breakdown voltages, ability to sustain large electric fields, lower electronic noise, and high-temperature and high-power operation. Most ZnO has n-type character, even in the absence of intentional doping. Nonstoichiometry is typically the origin of n-type character, but the subject remains controversial. Reliable p-type doping of ZnO remains difficult. This problem originates from low solubility of p-type dopants and their compensation by abundant n-type impurities. Current limitations to p-doping limit electronic and optoelectronic applications of ZnO, which usually require junctions of n-type and p-type material.
However, many of these form deep acceptors and do not produce significant p-type conduction at room temperature. ZnO discs, acting as a varistor, are the active material in most surge arresters. Zinc vapor reacts with the oxygen in the air to give ZnO, accompanied by a drop in its temperature and bright luminescence. Zinc oxide particles are transported into a cooling duct and collected in a bag house. 1844 and therefore is commonly known as the French process.
The direct or American process starts with diverse contaminated zinc composites, such as zinc ores or smelter by-products. A small amount of industrial production involves wet chemical processes, which start with aqueous solutions of zinc salts, from which zinc carbonate or zinc hydroxide is precipitated. Red and green color are associated with different concentrations of oxygen vacancies. Numerous specialised methods exist for producing ZnO for scientific studies and niche applications.