Pulsed laser heating in the diamond anvil cell: applications in geo- and material science

QUICK INFORMATION
Type
Seminar
Start Date
22-10-2019 09:00
End Date
22-10-2019 10:00
Location
Room 337, Central Building
Speaker's name
Georgios APRILIS
Speaker's institute
Laboratory of Crystallography, University of Bayreuth, Germany
Contact name
Claudine Roméro
Host name
Alexander Chumakov
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Modern high-pressure research demands studying various properties of materials in situ, inside diamond anvil cells (DACs), simultaneously at high temperature and high pressure. Among the two major methods of heating in DACs, are laser and resistive heating; laser heating has been already used for more than five decades and found numerous applications in mineral physics and high pressure chemistry, physics, Earths and materials sciences.

Additionally to the standard laser heating method of continuous-wave (CW) heating,   pulsed lasers have been used from the very first attempts of laser heating in a DAC, having the advantage of achieving significantly higher temperatures due to the concentration of a high laser power in a short impulse. Since the beginning of the 2000s, pulsed heating has been coupled with time-resolved measurements. The repetitive heating and cooling of the sample makes time an extra variable, additionally to pressure and temperature, something that is not possible with CW laser heating. A whole new field of research has been introduced, allowing determination of important material properties, such as thermal conductivity and diffusivity, and melting temperature. As another advantage, pulsed laser heating was thought to improve the chemical stability of the heated sample and its environment, by minimizing the heating time needed for a measurement.

We have developed a portable pulsed laser heating system that can be easily coupled with equipment at synchrotron facilities for time-resolved measurements, such as X-ray diffraction, Nuclear Inelastic Scattering (NIS) and Synchrotron Mössbauer Source (SMS), and X-ray Absorption Near Edge Structure spectroscopy (XANES) both at the European Synchrotron Radiation Facility (ESRF) and PETRA III at DESY. Investigations on the effect of pulsed laser heating on the stability of ferropericlase and the reaction of iron with carbon from the diamond anvils led to the conclusion that pulsed laser heating does not prevent and can possibly even accelerate chemical reactions inside the DAC, contrary to what was previously expected.

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