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 ...

Energy & Green Tech

EU proposes emission rules for last combustion engine cars

The European Union's executive arm proposed pollution standards Thursday for new combustion engine vehicles that are expected to remain on European roads well after the 27-nation bloc bans their sale in 2035.

Energy & Green Tech

Alternative to aviation fuel based on an oxygenated nanofluid

Aviation is a big user of fossil fuels and, as such, is a heavy producer of carbon emissions. Sustainability is high on the agenda. New work in the International Journal of Sustainable Aviation has reviewed the thermo-physical ...

Energy & Green Tech

Clear window coating could cool buildings without using energy

As climate change intensifies summer heat, demand is growing for technologies to cool buildings. Now, researchers report in ACS Energy Letters that they have used advanced computing technology and artificial intelligence ...

Energy & Green Tech

Researchers improve efficiency of low-cost solar cells

With global energy-related carbon dioxide emissions reaching an all-time high in 2021, the need for clean energy is more pressing than ever. One such alternative to fossil fuels is solar energy. Solar cells have been developed ...

Energy & Green Tech

Metal powder: Zero-carbon fuel for the future?

Gaining sustainable energy from wind, solar and water is commonly known and applied. However, renewable sources depend on environmental conditions: in peak times of wind and sun, excess energy is produced that is needed in ...

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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.

This text uses material from Wikipedia, licensed under CC BY-SA