High pressure
Template:Short description Template:About Template:Use mdy dates Template:Use American English In science and engineering, the study of high pressure examines its effects on materials and the design and construction of devices, such as a diamond anvil cell, which can create high pressure. High pressure usually means pressures of thousands (kilobars) or millions (megabars) ofTemplate:Nbsptimes atmospheric pressure (about Template:Convert).
History and overview
Percy Williams Bridgman received a Nobel Prize inTemplate:Nbsp1946 for advancing this area of physics by two magnitudes of pressure (Template:ValTemplate:Nbsp(MPa) toTemplate:NbspTemplate:ValTemplate:Nbsp(GPa)). The founders of this field include also Harry George Drickamer, Tracy Hall, Francis P. Bundy, Template:Ill, and Template:Ill.
It was by applying high pressure as well as high temperature to carbon that synthetic diamonds were first produced alongside 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 even higher pressure, 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 liable to change under high pressure, when the Template:MathTemplate:Nbspterm in the free energy becomes comparable to the energies of typical chemical bonds at around Template:Val. Among the most striking changes are metallization of oxygen atTemplate:NbspTemplate:Val (rendering oxygen a superconductor), and transition of sodium from a nearly-free-electron metal to a transparent insulator atTemplate:NbspTemplate:Approx. At ultimately high compression, however, all materials will metallize (Template:Xref).Template:Zwj<ref>Template:Cite journal</ref>
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 silicate 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.Template:Citation needed
Pressure "landmarks"
- Typical pressures reached by large-volume presses: upTemplate:Nbspto Template:Val
- Pressures that can be generated inside diamond anvil cells: Template:ApproxTemplate:Zwj<ref>Template:Cite journal</ref>
- Pressure at center of the Earth: Template:Val
- Highest pressures ever achieved in shock waves: overTemplate:NbspTemplate:ConvertTemplate:Zwj<ref>Template:Cite journal</ref>