Technical Summary: The simultaneous application of high pressures and temperatures to materials is being explored for technological reasons, and for basic research in physics, materials science, geophysics and chemistry. A laser heated diamond anvil cell is one way to achieve these extreme conditions in the laboratory. Current laser heating technology uses CW infrared lasers to irradiate samples that are pressurized inside of a diamond anvil cell. This technology is limited to temperatures of ~ 7,000 K; the limitation being imposed by the power of the lasers. We propose to develop a UV pulsed laser heating system to pursue laser heating of samples that are under high pressures while in a diamond anvil cell. The proposed system will allow for samples to be subjected to high pressures, and temperatures of greater than 20,000 K. The substantially higher temperature that will be reached with the UV laser is due to the combination of greater power available in a pulsed system, and that most materials have higher absorption coefficients in the UV than in the infrared. Sample temperatures and the temperature evolution will be determined by using a gated CCD to measure the emitted blackbody radiation. Initially the laser heating system will be used for synthesis of new nitride compounds which are expected to have unique properties, such as high hardness for the cases of WN2 and ?Ã’-C3N4. The proposed system, with its three-fold increase in accessible temperatures over current technology will also allow unprecedented advances in melting studies, phase diagrams, and equations of state. This will impact the fields of physics, materials science, chemistry and geoscience. Construction of, and research with, the proposed instrument will train graduate and undergraduate students in advanced instrumentation, scientific research, and will have broad societal impact.
Layman Summary: The simultaneous application of high pressures and high temperatures, has been shown to impact the properties of many materials. One of the best known examples of this is the conversion of graphite to diamond. This occurs inside the earth, producing natural diamonds, and beginning in 1955 researchers have been able to produce diamond from graphite by creating the necessary high pressure-high temperature conditions in the lab. In addition to advantageous structural changes (such as graphite to diamond), it has been shown that high pressures and high temperatures also change the chemistry of materials. For example, elements that do not normally bond can be made to combine, resulting in novel and potentially useful compounds. The proposed instrument will make it possible to study materials placed under pressures of up to one million atmospheres while at temperatures three times greater than has been achieved with conventional methods. The main innovation that will allow for such high temperatures is the use of short laser pulses of ultraviolet light which will be absorbed by the compressed materials and heat them. Upon completion of the proposed instrument, the initial experiments will be to synthesize new, useful compounds. The proposed technology will be used more broadly to determine how a variety of materials change under extreme conditions, which will advance the fields of physics, materials science, chemistry and geoscience. Construction of, and research with, the proposed instrument will train graduate and undergraduate students in advanced instrumentation, scientific research and will have broad societal impact.
