Light and sound waves reveal negative pressure

Negative pressure is a rare and challenging-to-detect phenomenon in physics. Using liquid-filled optical fibers and sound waves, researchers at the Max Planck Institute for the Science of Light (MPL) in Erlangen have now ...

Experts explain how diamonds are grown in a lab

A diamond is a solid rock of carbon and the hardest known naturally occurring substance. Because diamonds also have some extraordinary optical and physical properties, intensive research is underway on their use in laser ...

New research explains 'Atlantification' of the Arctic Ocean

New research by an international team of scientists explains what's behind a stalled trend in Arctic Ocean sea ice loss since 2007. The findings indicate that stronger declines in sea ice will occur when an atmospheric feature ...

Watching a bimetallic catalytic surface in action

A team of researchers from the Department of Interface Science at the Fritz Haber Institute of the Max Planck Society addressed the question: what happens to a Ga-promoted Cu surface under reaction conditions required for ...

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High pressure

High pressure science and engineering is studying the effects of high pressure on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. By high pressure it is usually meant pressures of thousands (kilobars) or millions (megabars) of times atmospheric pressure (about 1 bar).

It was by applying high pressure as well as high temperature to carbon that man-made diamonds were first produced as well as many other interesting discoveries. Almost any material when subjected to high pressure will compact itself into a denser form, for example, quartz, also called silica or silicon dioxide will first adopt a denser form known as coesite, then upon application of more temperature, form stishovite. These two forms of silica were first discovered by high pressure experimenters, but then found in nature at the site of a meteor impact.

Chemical bonding is likely to change under high pressure, when the P*V term in the free energy becomes comparable to the energies of typical chemical bonds - i.e. at around 100 GPa. Among the most striking changes are metallization of oxygen at 96 GPa (rendering oxygen a superconductor), and transition of sodium from a nearly-free-electron metal to a transparent insulator at ~200 GPa. At ultimately high compression, however, all materials will metallize.[citation needed]

High pressure experimentation has led to the discovery of the types of minerals which are believed to exist in the deep mantle of the Earth, such as perovskite which is thought to make up half of the Earth's bulk, and post-perovskite, which occurs at the core-mantle boundary and explains many anomalies inferred for that region.[citation needed]

Pressure "landmarks": pressure exerted by a fingernail scratching is ~0.6 GPa, typical pressures reached by large-volume presses are up to 30-40 GPa, pressures that can be generated inside diamond anvil cells are ~320 GPa, pressure in the center of the Earth is 364 GPa, highest pressures ever achieved in a shock waves are over 100,000 GPa.[citation needed]

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