High pressure is key for better optical fibers

Optical fiber data transmission can be significantly improved by producing the fibers, made of silica glass, under high pressure, researchers from Japan and the US report in the journal npj Computational Materials.

Natural nanodiamonds in oceanic rocks

Natural diamonds can form through low pressure and temperature geological processes on Earth, as stated in an article published in the journal Geochemical Perspectives Letters. The newfound mechanism, far from the classic ...

Scientists find upper limit for the speed of sound

A research collaboration between Queen Mary University of London, the University of Cambridge and the Institute for High Pressure Physics in Troitsk has discovered the fastest possible speed of sound.

New insights into the origin of diamonds in meteorites

Scientists have offered new insights into the origin of diamonds in ureilites (a group of stony meteorites). These diamonds most likely formed by rapid shock transformation from graphite (the common low-pressure form of pure ...

New study helps characterise the fusion of metals

In recent years, a great deal of effort has been devoted to the study of the melting curve of elements at high pressure. This information is relevant, for example, for applications such as nuclear fission reactors that involve ...

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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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