High pressure
hideHigh 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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News tagged with high pressure
Graphite oxide at high pressure opens a road to new amazing nano-materials
Nanotechnology / Nanomaterials
Dec 21, 2009 |
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(PhysOrg.com) -- New results by scientists at Umeľ University, Sweden, show that not only water but also alcohol solvents can be inserted to expand the structure of graphite oxide under high pressure conditions. The ...
Scientists Observe Liquid Water Below Freezing
Jun 24, 2009 |
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(PhysOrg.com) -- Below 0 °C, water turns to ice. But beyond that, or below about -75 °C, the ice may turn back into liquid water. While scientists have previously predicted this phase transition with computer ...
Water acts as catalyst in explosives
Mar 20, 2009 |
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The most abundant material on Earth exhibits some unusual chemical properties when placed under extreme conditions.
Metal Becomes Transparent Under High Pressure
Mar 12, 2009 |
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An international team of scientists have discovered a transparent form of the element sodium (Na). The team, led by Artem Oganov, Professor of Theoretical Crystallography at Stony Brook University, and Yanming ...
Under pressure, atoms make unlikely alloys
Mar 11, 2009 |
4.8 / 5 (12) |
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(PhysOrg.com) -- Ever since the Bronze Age, humans have experimented with combining different metals to create alloys with properties superior to either metal alone. But not all metals readily form alloys ...
Putting the Pressure on Iron-Based Superconductors
Mar 05, 2009 |
4.8 / 5 (9) |
3
(PhysOrg.com) -- Traditionally, magnetism and superconductivity don't mix. For more than 20 years, the only known superconductors that worked at so-called "high" temperatures (above 30 K, or about -406 degrees ...
An impossible alloy now possible
Feb 26, 2009 |
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What has been impossible has now been shown to be possible - an alloy between two incompatible elements. The findings are being published in this week's edition of Proceedings of the National Academy of Science, USA.
Researchers explain odd oxygen bonding under pressure
Aug 04, 2008 |
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Oxygen, the third most abundant element in the cosmos and essential to life on Earth, changes its forms dramatically under pressure transforming to a solid with spectacular colors. Eventually it becomes metallic ...
