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[[Image:Diamond Anvil Cell - Cross Section.svg|Diamond Anvil Cell – Cross Section|250px|thumb|Schematics of the core of a diamond anvil cell. The diamond size is a few millimeters at most]]
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A '''diamond anvil cell''' (DAC) is a device used in scientific experiments. It allows compressing a small (sub-[[millimeter]] sized) piece of material to [[Orders of magnitude (pressure)|extreme pressure]]s, which can exceed 300 [[Pascal (unit)|gigapascals]] (3,000,000  [[bar (unit)|bars]] / 2,960,770 [[atmosphere (unit)|atmospheres]]).<ref name=Hemley1998>{{cite doi|10.1063/1.882374}}</ref>
 
The device has been used to recreate the pressure existing deep inside [[planet]]s, creating materials and [[Phase (matter)|phases]] not observed under normal conditions. Notable examples include the non-molecular [[Ice#Phases|ice X]],<ref>{{cite journal|title = Compression of ice to 210 gigapascals: Infrared evidence for a symmetric hydrogen-bonded phase|journal = [[Science (journal)|Science]]|volume = 273|pages = 218–230|year = 1986|doi = 10.1126/science.273.5272.218|pmid = 8662500|month = Jul|issue = 5272|bibcode = 1996Sci...273..218G|last1 = Goncharov|first1 = A. F.|last2 = Struzhkin|first2 = V. V.|last3 = Somayazulu|first3 = M. S.|last4 = Hemley|first4 = R. J.|last5 = Mao|first5 = H. K. }}</ref> polymeric nitrogen<ref>{{cite journal|title = Semiconducting non-molecular nitrogen up to 240 GPa and its low-pressure stability|journal = [[Nature (journal)|Nature]]|volume = 411|year = 2001|pages = 170–174|doi = 10.1038/35075531|pmid = 11346788|month = May|last1 = Eremets|first1 = MI|last2 = Hemley|first2 = RJ|last3 = Mao|first3 = Hk|last4 = Gregoryanz|first4 = E|issue = 6834|bibcode = 2001Natur.411..170E }}</ref> and metallic [[xenon]] (an inert gas at lower pressures).
 
A DAC consists of two opposing [[diamond]]s with a sample compressed between the [[culet]]s. Pressure may be monitored using a reference material whose behavior under pressure is known. Common pressure standards include [[ruby]]<ref name=Forman1972>{{Cite journal|last1 = Forman|first1 = Richard A.|last2 = Piermarini|first2 = Gasper J.|last3 = Barnett|first3 = J. Dean|last4 = Block|first4 = Stanley|year = 1972|title = Pressure Measurement Made by the Utilization of Ruby Sharp-Line Luminescence|journal = Science|volume = 176|issue = 4032|pages = 284–5|doi = 10.1126/science.176.4032.284|pmid = 17791916|bibcode = 1972Sci...176..284F }}</ref> [[fluorescence]], and various [[Crystal structure|structurally]] simple metals, such as [[copper]] or [[platinum]].<ref name="isbn0-12-408950-X">{{cite book |author=Kinslow, Ray; Cable, A. J. |title=High-velocity impact phenomena |publisher=Academic Press |location=Boston |year=1970|isbn=0-12-408950-X}}</ref> The uniaxial pressure supplied by the DAC may be transformed into uniform [[Fluid statics#Hydrostatic pressure|hydrostatic pressure]] using a pressure transmitting medium, such as [[argon]], [[xenon]], [[hydrogen]], [[helium]], [[paraffin oil]] or a mixture of [[methanol]] and [[ethanol]].<ref name="jay1">{{cite journal|author = Jayaraman, A. |title = Ultrahigh pressures|journal = Reviews of Scientific Instruments|pages = 1013|year = 1986|issue = 6|doi = 10.1063/1.1138654|volume = 57|bibcode = 1986RScI...57.1013J }}</ref> The pressure-transmitting medium is enclosed by a gasket and the two diamond anvils. The sample can be viewed through the diamonds and illuminated by [[X-rays]] and visible light. In this way, [[X-ray diffraction]] and [[X-ray fluorescence|fluorescence]]; [[optical absorption]] and [[photoluminescence]]; [[Mössbauer spectroscopy|Mössbauer]], [[Raman scattering|Raman]] and [[Brillouin scattering]]; [[Positron annihilation spectroscopy|positron annihilation]] and other signals can be measured from materials under high pressure. Magnetic and microwave fields can be applied externally to the cell allowing [[nuclear magnetic resonance]], [[electron paramagnetic resonance]] and other magnetic measurements.<ref>{{cite journal|doi=10.1063/1.1143596|title=Enhanced sensitivity for high-pressure EPR using dielectric resonators|year=1992|last1=Bromberg|first1=Steven E.|journal=Review of Scientific Instruments|volume=63|issue=7|pages=3670|last2=Chan|first2=I. Y.|bibcode = 1992RScI...63.3670B }}</ref> Attaching [[electrodes]] to the sample allows electrical and [[Magnetoresistance|magnetoelectrical]] measurements as well as heating up the sample to a few thousand degrees. Much higher temperatures (up to 7000 K)<ref>{{cite journal|author=Chandra Shekar, N. V. ''et al.''|title=Laser-heated diamond-anvil cell (LHDAC) in materials science research|url=http://www.jmst.org/EN/abstract/abstract6706.shtml|journal=J. Mater. Sci. Techn.|volume=19|year=2003|page=518}}</ref> can be achieved with laser-induced heating,<ref>{{cite journal|author=Subramanian, N. et al. |title=Development of laser-heated diamond anvil cell facility for synthesis of novel materials|url=http://www.ias.ac.in/currsci/jul252006/175.pdf |journal=Current Science|volume= 91 |year=2006|page= 175}}</ref> and cooling down to millikelvins has been demonstrated.<ref name="jay1"/>
 
==Principle==
 
The operation of the diamond anvil cell relies on a simple principle:
 
:<math>p=\frac{F}{A}</math>
 
where ''p'' is the pressure, ''F'' the applied force, and ''A'' the area.
 
Therefore high pressure can be achieved by applying a moderate [[force]] on a sample with a small area, rather than applying a large force on a large area. In order to minimize deformation and failure of the [[anvil]]s that apply the force, they must be made from a very hard and virtually incompressible material, such as diamond.
 
==History==
[[image:First diamond anvil cell.jpg|thumb|250px|The first diamond anvil cell in the NIST museum of Gaithersburg. Shown in the image above is the part which compresses the central assembly.]]
 
[[Percy Williams Bridgman]], the great pioneer of high-pressure research during the first half of the 20th century, revolutionized the field of high pressures with his development of an opposed [[anvil]] device with small flat areas that were pressed one against the other with a lever-arm. The anvils were made of [[tungsten carbide]] (WC). This device could achieve [[pressure]] of a few [[Pascal (unit)|gigapascals]], and was used in [[electrical resistance]] and [[compressibility]] measurements. The invention of the diamond anvil cell in the late 1950s at the [[National Bureau of Standards]] (NBS) by Weir, Lippincott, Van Valkenburg, and Bunting further refined the process.<ref>[http://nvl.nist.gov/pub/nistpubs/sp958-lide/100-103.pdf The Diamond Anvil Pressure Cell]. NIST</ref> The principles of the DAC are similar to the Bridgman anvils but in order to achieve the highest possible pressures without breaking the [[anvil]]s, they were made of the hardest known material: a single [[crystal]] [[diamond]]. The first prototypes were limited in their pressure range and there was not a reliable way to [[calibrate]] the pressure. During the following decades DACs have been successively refined, the most important innovations being the use of [[gasket]]s and the [[ruby]] pressure calibration. The DAC evolved to be the most powerful lab device for generating static high pressure.<ref>{{cite journal|author = Block, S. and Piermarini, G. |title = The Diamond Cell Stimulates High-Pressure Research|journal = Physics Today|volume = 29|pages = 44|doi = 10.1063/1.3023899|year = 1976 | issue=9}}</ref> The range of static pressure attainable today extends to the estimated pressures at the Earth's center (~360 GPa).
 
==Components==
There are many different DAC designs but all have four main components:
 
# The [[force]]-generating device — relies on the operation of either a [[lever]] arm, tightening [[screw (simple machine)|screw]]s, or [[pneumatic]] or [[hydraulic]] [[pressure]] applied to a membrane. In all cases the [[force]] is [[uniaxial]] and is applied to the tables (bases) of the two [[anvil]]s
# Two opposing [[diamond]] [[anvil]]s — made of high [[Gemstone|gem]] quality, flawless diamonds, usually with 16 facets. They typically weigh 1/8 to 1/3 [[Carat (unit)|carat]] (25 to 70&nbsp;mg). The culet (tip) is ground and polished to a hexadecagonal surface parallel to the table. The culets of the two [[diamond]]s face one another, and must be perfectly [[parallel (geometry)|parallel]] in order to produce uniform [[pressure]] and to prevent dangerous [[Strain (materials science)|strains]]. Specially selected anvils are required for specific measurements—for example, low diamond absorption and luminescence is required in corresponding experiments.
# [[Gasket]] — a [[foil (chemistry)|foil]] of ~0.2&nbsp;mm thickness (before compression) that separates the two culets. It has an important role: to contain the sample with a [[hydrostatic fluid]] in a cavity between the [[diamond]]s, and to prevent anvil failure by supporting the [[diamond]] tips, thus reducing [[stress (physics)|stresses]] at the edges of the culet. Standard gasket materials are hard metals and their alloys, such as [[stainless steel]], [[Inconel]], [[rhenium]], [[iridium]] or [[tungsten carbide]]. They are not transparent to X-rays, and thus if X-ray illumination through the gasket is required then lighter materials, such as [[beryllium]], [[boron nitride]],<ref>{{cite journal|doi=10.1063/1.2917409|pmid=18513075|year=2008|last1=Funamori|first1=N|last2=Sato|first2=T|title=A cubic boron nitride gasket for diamond-anvil experiments|volume=79|issue=5|pages=053903|journal=The Review of scientific instruments|bibcode = 2008RScI...79e3903F }}</ref> [[boron]]<ref>{{cite journal|doi=10.1063/1.1621065|title=Amorphous boron gasket in diamond anvil cell research|year=2003|last1=Lin|first1=Jung-Fu|journal=Review of Scientific Instruments|volume=74|issue=11|pages=4732|last2=Shu|first2=Jinfu|last3=Mao|first3=Ho-Kwang|last4=Hemley|first4=Russell J.|last5=Shen|first5=Guoyin|bibcode = 2003RScI...74.4732L }}</ref> or [[diamond]]<ref>{{cite journal|doi=10.1063/1.1343864|title=A diamond gasket for the laser-heated diamond anvil cell|year=2001|last1=Zou|first1=Guangtian|journal=Review of Scientific Instruments|volume=72|issue=2|pages=1298|last2=Ma|first2=Yanzhang|last3=Mao|first3=Ho-Kwang|last4=Hemley|first4=Russell J.|last5=Gramsch|first5=Stephen A.|bibcode = 2001RScI...72.1298Z }}</ref> are used as a gasket.
# Pressure-transmitting medium — homogenizes the pressure. Methanol:ethanol 4:1 mixture is rather popular because of ease of handling. However, above ~20 GPa it turns into a glass and thus the pressure becomes nonhydrostatic.<ref name="jay1"/> [[Argon]], [[hydrogen]] and [[helium]] are usable up to the highest pressures, and ingenious techniques have been developed to seal them in the cell.<ref name="jay1"/>
 
==Uses==
Prior to the invention of the diamond anvil cell, static high-pressure apparatus required large hydraulic presses which weighed several tons and required large specialized laboratories. The simplicity and compactness of the DAC meant that it could be accommodated in a wide variety of experiments. Some contemporary DACs can easily fit into a [[cryostat]] for low-temperature measurements, and for use with a [[superconducting]] [[electromagnet]]. In addition to being hard, [[diamonds]] have the advantage of being transparent to a wide range of the [[electromagnetic spectrum]] from [[infrared]] to [[gamma rays]], with the exception of the far [[ultraviolet]] and soft [[X-rays]]. This makes the DAC a perfect device for [[spectroscopic]] experiments and for [[crystallography|crystallographic studies]] using hard [[X-rays]].
 
A variant of the diamond anvil, the hydrothermal diamond anvil cell (HDAC) is used in experimental petrology/geochemistry for the study of aqueous fluids, silicate melts, immiscible liquids, mineral solubility and aqueous fluid speciation at geologic pressures and temperatures. The HDAC is sometimes used to examine aqueous complexes in solution using the synchrotron light source techniques [[XANES]] and [[EXAFS]]. The design of HDAC is very similar to that of DAC, but it is optimized for studying liquids.<ref>{{cite journal|author=Bassett, W.A. ''et al.''|title=A new diamond anvil cell for hydrothermal studies to 2.5 GPa and from −190 to 1200 °C|doi=10.1063/1.1143931|year=1993|journal=Review of Scientific Instruments|volume=64|issue=8|pages=2340|bibcode = 1993RScI...64.2340B }}</ref>
 
==Innovative uses==
 
An innovative use of the diamond anvil cell is testing the sustainability and durability of life under [[high pressure]]s. This innovative use can be used in the search for life on [[extrasolar planets]]. One reason the DAC is applicable for testing life on extrasolar planets is [[panspermia]], a form of [[interstellar travel]]. When panspermia occurs, there is high pressure upon impact and the DAC can replicate this pressure. Another reason the DAC is applicable for testing life on extrasolar planets is that planetary bodies that hold the potential for life may have incredibly high pressure on their surface.
Anurag Sharma, a [[geochemistry|geochemist]], James Scott, a [[microbiology|microbiologist]], and others at the [[Carnegie Institution of Washington]] performed an experiment with the DAC using this new innovative application. Their goal was to test microbes and discover under what level of pressure they can carry out life processes. The experiment was performed under 1.6 [[GPa]] of pressure, which is more than 16,000 times [[Earth]]’s surface pressure (Earth’s surface pressure is 985 hPa). The experiment began by placing a solution of bacteria, specifically [[Escherichia coli]] and [[Shewanella oneidensis]], in a film and placing it in the DAC. The pressure was then raised to 1.6 GPa. When raised to this pressure and kept there for 30 hours, only about 1% of the bacteria survived. The experimenters then added a dye to the solution. If the cells survived the squeezing and were capable of carrying out life processes, specifically breaking down [[formate]], the dye would turn clear. 1.6 GPa is such great pressure that during the experiment the DAC turned the solution into [[Ice#Phases|ice-IV]], a room-temperature ice. When the bacteria broke down the formate in the ice, liquid pockets would form because of the chemical reaction. The bacteria were also able to cling to the surface of the DAC with their tails.<ref name="couz">{{cite journal|author = Couzin, J. |title = Weight of the world on microbes' shoulders|journal = Science|pages = 1444–1445|year = 2002|doi=10.1126/science.295.5559.1444b|volume = 295|issue = 5559|pmid = 11859165 }}</ref>
However, there is some skepticism with this experiment. People debate whether carrying out the simple process of breaking down formate is enough to consider the bacteria living. Art Yayanos, an oceanographer at the [[Scripps Institute of Oceanography]] in La Jolla, California, believes an organism should only be considered living if it can reproduce. Another issue with the DAC experiment is that when high pressures occur, there are usually high temperatures present as well, but in this experiment there were not. This experiment was performed at room-temperature, which causes some skepticism of the results.<ref name ="couz"/>
 
Moving past the 10 years of skepticism, new results from independent research groups <ref name="vanlint">{{cite journal|author = Vanlinit, D. et al. |title = Rapid Acquisition of Gigapascal-High-Pressure Resistance by Escherichia coli|journal = mBio|pages = e00130-10|year = 2011|doi= 10.1128/mBio.00130-10|volume = 2|issue = 1}}</ref> have shown the validity of Sharma et al. (2002) <ref name="sharma">{{cite journal|author = Sharma, A., et al. |title = Microbial activity at Gigapascal pressures|journal = Science|pages = 1514–1516|year = 2002|doi=10.1126/science.1068018|volume = 295|issue = 5559|pmid = 11859192|bibcode = 2002Sci...295.1514S }}</ref> work.  This is a significant step that reiterates the need for a new approach to the old problem of studying environmental extremes through experiments.  There is practically no debate whether microbial life can survive pressures up to 600 MPa, which has been shown over the last decade or so to be valid through a number of scattered publications.<ref name="sharma">{{cite journal|author = Sharma, A., et al. |title = Microbial activity at Gigapascal pressures|journal = Science|pages = 1514–1516|year = 2002|doi=10.1126/science.1068018|volume = 295|issue = 5559|bibcode = 2002Sci...295.1514S|pmid=11859192}}</ref> What is significant in this approach of Sharma et al. 2002 work is the elegantly straightforward ability to monitor systems at extreme conditions that have since remained technically inaccessible. While the simplicity and the elegance of this experimental approach is mind boggling; the results are rather expected and consistent with most biophysical models.  This novel approach lays a foundation for future work on microbiology at non-ambient conditions by not only providing a scientific premise, but also laying the technical feasibility for future work on non-ambient biology and organic systems.
 
There is another group of scientists performing similar tests with a low-pressure diamond anvil cell. This low-pressure DAC has better imaging quality and signal collection. It is designed to sense pressures in the 0.1–600 MPa range, much lower than the high pressure DAC. The new low-pressure DAC also has a new asymmetric design, as opposed to a symmetric design the old, high pressure DAC used. In this experiment [[Saccharomyces cerevisiae]] is the microbe being observed. Saccharomyces cerevisiae is more commonly known as baker’s yeast. These microbes can only grow in pressures ranging from 15–50 MPa, while pressures over 200 MPa are likely to kill the cells. The microbes were also incubated at 30 °C. Their tests showed that the yeast completed its cell cycle in 97±5 minutes.<ref>{{cite journal|title = Development of a low-pressure diamond anvil cell and analytical tools to monitor microbial activities in situ under controlled p and t|journal = Biochimica et Biophysica Acta (BBA)|volume = 1764|pages = 434–442–230|year = 2006|doi = 10.1016/j.bbapap.2005.11.009|issue = 3|last1 = Oger|first1 = Phil M.|last2 = Daniel|first2 = Isabelle|last3 = Picard|first3 = Aude |pmid=16388999|url=http://hal.archives-ouvertes.fr/docs/00/09/35/86/PDF/Oger_BBA_pro_Formate.pdf}}</ref>
In June 2013, Chrystèle Sanloup et al. reported using a diamond anvil cell to create reactions between [[Xenon]] and [[ice]] (the solid state of [[water]]) to create a compound of xenon, oxygen and hydrogen at pressures above 50 [[Pascal (unit)|GPa]] and a temperature of 1500 [[Kelvin (unit)|K]], that are conditions found in the interiors of the [[Solar System]]'s [[gas giant]] planets, [[Uranus]] and [[Neptune]]. X-ray [[crystallography]] data was used to determine a hexagonal lattice with four xenon atoms per unit cell. The results are consistent with the compound being Xe<sub>4</sub>O<sub>12</sub>H<sub>12</sub>, and lead to the conjecture that xenon is expected to be depleted in the atmospheres of the giant planets as a result of sequestration at depth.
<ref>[http://prl.aps.org/abstract/PRL/v110/i26/e265501 Reactivity of Xenon with Ice at Planetary Conditions], [[Chrystèle Sanloup]] et al, [[Americam Physical Society]] [[Physical Review Letters]], 10.1103/PhysRevLett.110.265501, 24 June 2013, accessed 10 July 2013</ref><ref>[http://theconversation.com/impossible-chemistry-making-the-unreactive-react-15272 Impossible chemistry: making the unreactive, react], Helen Maynard-Casely, [[The Conversation (website)|The Conversation]], 18 June 2013, accessed 10 July 2013</ref>
 
==See also==
{{Commons category|Diamond anvil cell}}
{{colbegin|3}}
*[[Anvil press]]
*[[High pressure]]
*[[Pressure experiment]]
*[[Fluid statics]]
*[[Material properties of diamond]]
{{colend}}
 
==References==
{{reflist|35em}}
 
==External links==
*[http://www.crystal.vt.edu/crystal/dac.html The Diamond-Anvil Cell] – Crystallography Laboratory at Virginia Tech.
*{{cite web|url = http://www.llnl.gov/str/December04/Weir.html|title = Putting the Squeeze on Materials|accessdate=2009-05-05}}
 
{{DEFAULTSORT:Diamond Anvil Cell}}
[[Category:Materials science]]
[[Category:Condensed matter physics]]
[[Category:Geophysics]]
[[Category:Physical chemistry]]

Latest revision as of 13:24, 6 November 2014



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