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]
For more information about High pressure, read the full article at
Wikipedia.
This text uses material from Wikipedia and is available under the GNU Free Documentation License.
News tagged with high pressure
Graphite oxide at high pressure opens a road to new amazing nano-materials
Nanotechnology / Nanomaterials
Dec 21, 2009 |
5 / 5 (2) |
1
(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 ...
Search results for high pressure
Sun and moon trigger deep tremors on San Andreas Fault
Space & Earth / Earth Sciences
Dec 23, 2009 |
4 / 5 (4) |
1
The faint tug of the sun and moon on the San Andreas Fault stimulates tremors deep underground, suggesting that the rock 15 miles below is lubricated with highly pressurized water that allows the rock to slip with little ...
Study shows a key protein helps control blood pressure
Dec 23, 2009 |
4.5 / 5 (2) |
0
University of Iowa researchers have shown that a protein channel helps nerve sensors in blood vessels keep blood pressure in check. Without the protein channel, known as ASIC2, the sensors are unable to send the brain the ...
High-blood-pressure treatment for the over-80s too aggressive, warns expert
Dec 23, 2009 |
4 / 5 (4) |
1
People over 80 years are being treated too aggressively for high blood pressure, warns an expert in an editorial in BMJ Clinical Evidence this week.
The number of 85-year-olds will increase by a third by 2020
Dec 23, 2009 |
5 / 5 (1) |
0
Health and social care provision needs to be put in place for a large increase (33%) in the 85 year old population in the UK by 2020, according to a study published today in the British Medical Journal.
Temp workers not stuck in jobs and earn more than regular employees
Dec 21, 2009 |
1.5 / 5 (2) |
1
(PhysOrg.com) -- Rather than being trapped in dead-end jobs, many people hired by temporary help agencies actually earn higher hourly wages and are better educated than permanent employees, and move quickly between temporary ...
What's in health care proposals for 5 Americans
Dec 20, 2009 |
2 / 5 (1) |
9
(AP) -- As Congress gets closer to a final health care bill, many Americans want to know: What's in it for me?
Obama hails 60th Senate vote for health care
Dec 19, 2009 |
2.3 / 5 (3) |
9
(AP) -- Jubilant Democrats locked in Nebraska Sen. Ben Nelson as the 60th and decisive vote for historic health care legislation Saturday, putting President Barack Obama's signature issue firmly on a path ...
Are patients losing sleep over blood pressure monitors?
Dec 17, 2009 |
not rated yet |
0
A widely used test for measuring nighttime blood pressure may interfere with patients' sleep, thus affecting the results of the test, reports a study in an upcoming issue of Clinical Journal of the American Society of Ne ...
Oracle expects EU to approve Sun deal next month
Dec 17, 2009 |
not rated yet |
0
(AP) -- Oracle Corp. said Thursday that its profit jumped 12.5 percent in the latest quarter and that it expects the European Union will finally approve its $7.4 billion purchase of Sun Microsystems Inc. ...
A Search for Stability for Platinum Catalysts
Nanotechnology / Nanomaterials
Dec 17, 2009 |
5 / 5 (1) |
0
(PhysOrg.com) -- A new carbon support that greatly increases the durability of proton-exchange membrane fuel cells has been developed by scientists at Pacific Northwest National Laboratory and Princeton University. ...
List of search results for high pressure
