Inscience andengineering, the study ofhigh pressure examines its effects on materials and the design and construction of devices, such as adiamond anvil cell, which can create highpressure.High pressure usually means pressures of thousands (kilobars) or millions (megabars) of timesatmospheric pressure (about 1bar or 100kilopascals).
Percy Williams Bridgman receiveda Nobel Prize in 1946 for advancing this area of physics by two magnitudes of pressure (400 megapascals (MPa) to 40 gigapascals (GPa)). The founders of this field include alsoHarry George Drickamer,Tracy Hall,Francis P. Bundy,Leonid F. Vereschagin [ru], andSergey M. Stishov [ru].
It was by applying high pressure as well as high temperature tocarbon thatsynthetic 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 calledsilica orsilicon dioxide) will first adopt a denser form known ascoesite, then upon application of even higher pressure, formstishovite. These two forms of silica were first discovered by high-pressure experimenters, but then found in nature at the site of ameteor impact.
Chemical bonding is liable to change under high pressure, when theP * V term in the free energy becomes comparable to the energies of typical chemical bonds at around100 GPa. Among the most striking changes are metallization ofoxygen at 96 GPa (rendering oxygen asuperconductor), and transition ofsodium from a nearly-free-electron metal to a transparent insulator at ~200 GPa. At ultimately high compression, however, all materials will metallize (seemetallization pressure).[1]
High-pressure experimentation has led to the discovery of the types of minerals which are believed to exist in thedeep mantle of the Earth, such assilicate perovskite, which is thought to make up half of the Earth's bulk, andpost-perovskite, which occurs at thecore-mantle boundary and explains many anomalies inferred for that region.[citation needed]
