Diamond die cell
A diamond punch cell (DAC, from English diamond anvil cell ), also a diamond punch press, is a device for compressing small material samples at very high pressure . It is used in scientific experiments . The pressures that are reached are in the gigapascal range, which corresponds to 10,000 times the pressure of the earth's atmosphere . At these pressures, for example, graphite is converted into diamond and minerals are created with crystal structures that do not exist on the earth's surface.
construction
A diamond die cell consists of two opposing cut diamonds ( brilliant- cut diamonds ) with the material sample between the culets (tips). The pressure is achieved by compressing the sealed sample set with the aid of hydraulic apparatus , whereby argon , xenon , hydrogen , helium , paraffin oil or a mixture of methanol and ethanol are used as the transmission medium between the diamonds .
business
The magnitude of the pressure achieved in the material sample is determined from a comparison with a reference material whose behavior under pressure is known.
The sample or its behavior can be observed and measured through the diamonds, using X-rays , visible light and other electromagnetic waves.
Attaching electrodes to the sample material allows measurements and heating of the sample to a few thousand degrees Celsius. Temperatures of up to 7000 degrees Celsius in the sample are achieved with laser-induced heating.
In the service of geosciences
Diamond anvil cells are used by geochemists and geophysicists within mineralogy as part of geomaterial research for laboratory experiments . These experiments are intended to answer the question of which substances are formed under the extremely high pressure and temperature conditions that prevail in the Earth's interior and what physical and chemical properties they have. Special high-performance diamond die cells, in which the highest pressures are concentrated on an area that is less than a square millimeter, deliver up to several million atmospheres in the pressure cell and, by means of laser heating, temperatures of several thousand degrees Celsius. Since the samples can no longer be seen with the naked eye, microscopic techniques, X-ray spectroscopy and laser spectroscopy are used to analyze the results. The interest ranges from the investigation of metamorphic rock formation to the fundamental question of how the original magma of the earth separated into a metallic core and a liquid, viscous silicate melt due to the sinking of the heavier metal melt from the less dense silicate environment. There is also interest in the distribution of elements between silicate and metal melts, their viscosity and the heat transport in minerals and melts. These questions are of fundamental importance for understanding earth dynamics. Experiments with diamond anvil cells are also used to check ab initio molecular dynamics simulations.
literature
- Aiyasami Jayaraman: Ultra high pressures. Review of Scientific Instruments, Volume 57, June 1986, ISSN 0034-6748, pp. 1013-1031.
- The Diamond Anvil Pressure Cell , Review from the National Institute of Standards and Technology
Web links
Individual evidence
- ↑ Sandro Jahn: Fingerprints from the depths. In: Research - The magazine of the German Research Foundation of October 4, 2013, pp. 24–27, doi : 10.1002 / fors.201390047