A greener internet of things with no wires attached

Emerging forms of thin-film device technologies that rely on alternative semiconductor materials, such as printable organics, nanocarbon allotropes and metal oxides, could contribute to a more economically and environmentally ...

Electronics & Semiconductors

Developing thermally evaporated environment-friendly semiconductors

Semiconductors are indispensable products in our lives, used in everything from smartphones and computers to vehicles. However, their development increasingly poses a problem: as semiconductors improve in terms of function ...


New materials for the computer of the future

Novel materials could revolutionize computer technology. Research conducted by scientists at the Paul Scherrer Institute PSI using the Swiss Light Source SLS has reached an important milestone along this path.

Electronics & Semiconductors

Building a 900-pixel imaging sensor using an atomically thin material

A team of researchers at Penn State University has developed a 900-pixel imaging sensor using an atomically thin material. In their paper published in the journal Nature Materials, the group describes how they built their ...

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An oxide ( /ˈɒksaɪd/) is a chemical compound that contains at least one oxygen atom in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2.

Most of the Earth's crust consists of solid oxides. Oxides result when elements are oxidized by oxygen in air. Combustion of hydrocarbons affords the two principal oxides of carbon, carbon monoxide and carbon dioxide. Even materials that are considered to be pure elements often contain a coating of oxides. For example, aluminium foil has a thin skin of Al2O3 that protects the foil from further corrosion.

Virtually all elements burn in an atmosphere of oxygen, or an oxygen rich environment. In the presence of water and oxygen (or simply air), some elements—lithium, sodium, potassium, rubidium, caesium, strontium and barium—react rapidly, even dangerously, to give the hydroxides. In part for this reason, alkali and alkaline earth metals are not found in nature in their metallic, i.e., native, form. Caesium is so reactive with oxygen that it is used as a getter in vacuum tubes, and solutions of potassium and sodium, so called NaK are used to deoxygenate and dehydrate some organic solvents. The surface of most metals consists of oxides and hydroxides in the presence of air. A well known example is aluminium foil, which is coated with a thin film of aluminium oxide that passivates the metal, slowing further corrosion. The aluminium oxide layer can be built to greater thickness by the process of electrolytic anodising. Although solid magnesium and aluminium react slowly with oxygen at STP, they, like most metals, will burn in air, generating very high temperatures. Finely grained powders of most metals can be dangerously explosive in air. Consequently, they are often used in Solid-fuel rockets.

In dry oxygen, iron readily forms iron(II) oxide, but the formation of the hydrated ferric oxides, Fe2O3−2x(OH)x, that mainly comprise rust, typically requires oxygen and water. The production of free oxygen by photosynthetic bacteria some 3.5 billion years ago precipitated iron out of solution in the oceans as Fe2O3 in the economically important iron ore hematite.

Due to its electronegativity, oxygen forms chemical bonds with almost all elements to give the corresponding oxides. Noble metals (such as gold or platinum) resist direct chemical combination with oxygen, and substances like gold(III) oxide must be generated by indirect routes.

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