The development of internal pressure standards for in-house elastic wave velocity measurements in multi-anvil presses.

Ultrasonic systems are powerful tools to determine elastic wave velocities of minerals and materials at high pressure and temperature and have been extensively developed in recent decades. However, accurate measurement of sample length is required to convert travel times into wave velocities, limiting their use to synchrotron facilities or room temperature experiments in laboratories. We have made use of a close collaboration between the Bayerisches Geoinstiut and the P61B end-station beamline (PETRA III - DESY) to install ultrasonic systems and develop a novel dual travel time method for in situ pressure determination without the need for synchrotron radiation. Our method relies on the travel times of elastic waves through a reference material; it requires a thermocouple and is non-intrusive, with the reference material replacing the backing plate of the high-pressure assembly. Pressures obtained from this dual travel time method show excellent agreement with those obtained from x-ray diffraction using synchrotron radiation on standard materials. Our novel method enables in situ pressure determination at varying temperatures during in-house ultrasonic interferometry experiments. This allows us not only to determine the elastic behavior of minerals and materials but also to investigate phase diagrams, solidus, or liquidus conditions at varying pressures and temperatures during in-house experiments. During the installation of the pulse-echo ultrasonic system, we identified critical parameters for obtaining reliable data. While these requirements are well-known to experts, this study presents a comprehensive review of the different characteristics of ultrasonic systems, providing user-friendly guidelines for new users installing and operating such systems in high-pressure and high-temperature conditions.

Portable double-sided laser-heating system for Mössbauer spectroscopy and X-ray diffraction experiments at synchrotron facilities with diamond anvil cells.

The diamond anvil cell (DAC) technique coupled with laser heating is a major method for studying materials statically at multimegabar pressures and at high temperatures. Recent progress in experimental techniques, especially in high-pressure single crystal X-ray diffraction, requires portable laser heating systems which are able to heat and move the DAC during data collection. We have developed a double-sided laser heating system for DACs which can be mounted within a rather small (~0.1 m(2)) area and has a weight of ~12 kg. The system is easily transferable between different in-house or synchrotron facilities and can be assembled and set up within a few hours. The system was successfully tested at the High Pressure Station of White Beam (ID09a) and Nuclear Resonance (ID18) beamlines of the European Synchrotron Radiation Facility. We demonstrate examples of application of the system to a single crystal X-ray diffraction investigation of (Mg(0.87),Fe(3+) (0.09),Fe(2+) (0.04))(Si(0.89),Al(0.11))O(3) perovskite (ID09a) and a Synchrotron Mössbauer Source (SMS) study of (Mg(0.8)Fe(0.2))O ferropericlase (ID18).