Laser heating setup for diamond anvil cells for in situ synchrotron and in house high and ultra-high pressure studies

Abstract

The diamond anvil cell (DAC) technique combined with laser heating is one of the major methods for studying materials at high pressure and high temperature conditions. In this work, we present a transferable double-sided laser heating setup for DACs with in situ temperature determination. The setup allows precise heating of samples inside a DAC at pressures above 200 GPa and could be combined with synchrotron beamline equipment. It can be applied to X-ray diffraction and X-ray transmission microscopy experiments. In the setup, we use high-magnification and low working distance infinity corrected laser focusing objectives that enable us to decrease the size of the laser beam to less than 5 µm and achieve the maximum optical magnification of 320 times. All optical components of the setup were chosen to minimize chromatic and spatial aberrations for accurate in situ temperature determination by multiwavelength spectroscopy in the 570–830 nm spectral range. Flexible design of our setup allows simple interchange of laser sources and focusing optics for application in different types of studies. The setup was successfully tested in house and at the high-pressure diffraction beamline ID15B at the European Synchrotron Radiation Facility. We demonstrate an example of application of the setup for the high pressure–high temperature powder diffraction study of PdH and X-ray transmission microscopy of platinum at 22(1) GPa as a novel method of melting detection in DACs.

Synthesis, crystal structure and structure–property relations of strontium orthocarbonate, Sr2CO4

“…The in situ sample pressure was determined using the known equation of state of gold, also loaded in the sample cavity in the form of micrograins (Dewaele et al, 2008). The sample was compressed to 92 GPa and laser heated to a temperature of 2500 K. Measuring the thermal radiation produced by the sample enabled the accurate determination of its temperature (Fedotenko et al, 2019). Under these conditions, strontium carbonate reacted to produce strontium orthocarbonate (Sr 2 CO 4 ).…”

High-Pressure Polymeric Nitrogen Allotrope with the Black Phosphorus Structure

“…The cell was then loaded with pure nitrogen gas at ∼1200 bars. The sample was compressed to 124 GPa and laser heated, reaching a maximum temperature of 2600 K as determined by thermoemission measurements [32]. Weak diffraction spots appeared after laser heating but could not be indexed using any of the known phases of molecular or polymeric nitrogen, gold, or rhenium.…”

Novel Rhenium Carbides at 200 GPa

“…After the first heating attempt pressure dropped down to ≈ 200 GPa probably due to failure of the secondary anvils. However, the DAC remained intact and rhenium in the central area was again carefully laser heated in a pulsed mode (1 µs pulses, 25 kHz repetition rate, and maximum temperature of 3000 ± 300 K) . Pressure did not change upon the repeated laser heating (Supporting Information, Figure S1) and the DAC with the temperature‐quenched material was investigated using powder and single‐crystal X‐ray diffraction (for details see the Supporting Information).…”