Metal–silicate partitioning studies performed in high-pressure, laser-heated diamond anvil cells (DAC) are commonly used to explore element distribution during planetary-scale core–mantle differentiation. The small run-products contain suitable areas for analysis commonly less than tens of microns in diameter and a few microns thick. Because high spatial resolution is required, quantitative chemical analyses of the quenched phases is usually performed by electron probe microanalysis (EPMA). Here, EPMA is being used at its spatial limits, and sample thickness and secondary fluorescence effects must be accounted for. By using simulations and synthetic samples, we assess the validity of these measurements, and find that in most studies DAC sample wafers are sufficiently thick to be characterized at 15 kVacc. Fluorescence from metal-hosted elements will, however, contaminate silicate measurements, and this becomes problematic if the concentration contrast between the two phases is in excess of 100. Element partitioning experiments are potentially compromised; we recommend simulating fluorescence and applying a data correction, if required, to such DAC studies. Other spurious analyses may originate from sources external to the sample, as exemplified by 0.5 to >1 wt% of Cu arising from continuum fluorescence of the Cu TEM grid the sample is typically mounted on.

The clinopyroxenes kanoite and spodumene were studied by single-crystal X-ray diffraction in a diamond anvil cell (DAC) at room temperature. At the displacive phase transitions between the C2/c and P21/c polymorphs both phases coexist within the same crystal. In this two-phase region the pressure in the DAC remains constant. The experimental results demonstrate that pressure buffering at first-order phase transitions can occur in the DAC.

The high-pressure behaviour of manganese carbonate was investigated by in situ synchrotron X-ray powder diffraction up to 54 GPa with a laser-heated diamond anvil cell. A phase transition from rhodochrosite to a new structure form was observed at 50 GPa after laser heating. The diffraction pattern of the new high-pressure form was reasonably indexed with an orthorhombic unit-cell with a = 5.361 A, b = 8.591 A and c = 9.743 Å. The pressure-induced phase transition implies a unit-cell volume reduction of ∼5%. This result does not support the direct formation of diamond by dissociation of solid state MnCO3 reported in a previous study. Fitting the compression data of rhodochrosite to a second-order Birch-Murnaghan equation of state (Ko’ = 4) gives K0 = 126(±10) GPa. The c axis of the unit-cell parameter was more compressive than the a axis.

Synchrotron X-ray diffraction images are increasingly used to characterize crystallographic preferred orientation distributions (texture) of fine-grained polyphase materials. Diffraction images can be analyzed quantitatively with the Rietveld method as implemented in the software package Materials Analysis Using Diffraction. Here we describe the analysis procedure for diffraction images collected with high energy X-rays for a complex, multiphase shale, and for those collected in situ in diamond anvil cells at high pressure and anisotropic stress.

This paper suggests a novel route to approach the cold compression curve in laser-plasma induced shock waves. This effect is achieved with a precompression in a diamond anvil cell (DAC). In order to keep the necessary structure of one dimensional shock wave it is required to use a diamond anvil cell with a partially perforated diamond anvil. Precompression pressures of about 50 GPa, that are an order of magnitude higher than the currently reported pressures, are possible to obtain with presentley existing diamond anvil cell technology. The precompressed Hugoniot of Al was calculated for different precompression pressures and it was found that at precompression pressure of 50 GPa the Hugoniot follows the “cold curve” up to about 2 Mbar and 5.2 g/cc. Furthermore, the thermal relative contribution on the Hugoniot curves is calculated.

An incident beam X-ray collimator for Mao-Bell type diamond anvil cell (DAC) has been developed. Alignment of the collimator is carried out in situ while viewing the image of the collimated X-ray spot formed on a thin layer of fluorescent material spread on the diamond anvil culets with the help of a microscope. Special precaution has been taken to meet the radiation safety requirements during alignment and routine use. This collimator is of immense help for laboratory based high pressure X-ray diffraction experiments.

The method of high-energy total elastic X-ray scattering to determine the atomic structure of nanocrystalline, highly disordered, and amorphous materials is presented. The current state of the technique, its potential, and limitations are discussed with two successful studies on the pressure induced phase transition in mackinawite (FeS) and the high-pressure behavior of liquid gallium.