Publications by authors named "R Farla"

This study reports the synthesis and crystal structure determination of a novel CrTe phase using various experimental and theoretical methods. The average stoichiometry and local phase separation of this quenched high-pressure phase were characterized by synchrotron powder X-ray diffraction and total scattering. Several structural models were obtained using simulated annealing, but all suffered from an imperfect Rietveld refinement, especially at higher diffraction angles.

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SnGeNO was synthesized at high pressure (16 and 20 GPa) and high temperature (1200 and 1500°C) in a large-volume press. Powder X-ray diffraction experiments using synchrotron radiation indicate that the derived samples are mixtures of known and unknown phases. However, the powder X-ray diffraction patterns are not sufficient for structural characterization.

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We have performed in situ X-ray diffraction measurements of cubic silicon carbide (SiC) with a zinc-blende crystal structure (B3) at high pressures and temperatures using multi-anvil apparatus. The ambient volume inferred from the compression curves is smaller than that of the starting material. Using the 3-order Birch-Murnaghan equation of state and the Mie-Grüneisen-Debye model, we have determined the thermoelastic parameters of the B3-SiC to be K=228±3 GPa, K',=4.

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High-pressure, high-temperature (HP/HT) syntheses are essential for modern high-performance materials. Phosphorus nitride, nitridophosphate, and more generally nitride syntheses benefit greatly from HP/HT conditions. In this contribution, we present the first systematic investigation of a nitridophosphate HP/HT synthesis using the reaction of zinc nitride ZnN and phosphorus(V) nitride PN to the nitride semiconductor ZnPN as a case study.

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Article Synopsis
  • Ultrasonic systems have become essential tools for measuring elastic wave velocities in minerals and materials under high pressure and temperature, but accurate sample length measurements have limited their use to specialized facilities or controlled lab environments.
  • A collaboration between Bayerisches Geoinstitut and DESY has led to the development of a novel dual travel time method that allows for accurate in situ pressure determination without needing synchrotron radiation, using a non-intrusive approach with a reference material.
  • This new method enhances the capability of in-house ultrasonic experiments by enabling pressure measurement at varying temperatures, facilitating the study of materials' elastic behavior and phase diagrams under different conditions while providing user-friendly guidelines for reliable data collection in extreme conditions.
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