A new facility for microdiffraction strain measurements and microfluorescence mapping has been built on beamline 12.3.2 at the advanced light source of the Lawrence Berkeley National Laboratory. This beamline benefits from the hard x-radiation generated by a 6 T superconducting bending magnet (superbend). This provides a hard x-ray spectrum from 5 to 22 keV and a flux within a 1 μm spot of ∼5×109 photons/s (0.1% bandwidth at 8 keV). The radiation is relayed from the superbend source to a focus in the experimental hutch by a toroidal mirror. The focus spot is tailored by two pairs of adjustable slits, which serve as secondary source point. Inside the lead hutch, a pair of Kirkpatrick–Baez (KB) mirrors placed in a vacuum tank refocuses the secondary slit source onto the sample position. A new KB-bending mechanism with active temperature stabilization allows for more reproducible and stable mirror bending and thus mirror focusing. Focus spots around 1 μm are routinely achieved and allow a variety of experiments, which have in common the need of spatial resolution. The effective spatial resolution (∼0.2 μm) is limited by a convolution of beam size, scan-stage resolution, and stage stability. A four-bounce monochromator consisting of two channel-cut Si(111) crystals placed between the secondary source and KB-mirrors allows for easy changes between white-beam and monochromatic experiments while maintaining a fixed beam position. High resolution stage scans are performed while recording a fluorescence emission signal or an x-ray diffraction signal coming from either a monochromatic or a white focused beam. The former allows for elemental mapping, whereas the latter is used to produce two-dimensional maps of crystal-phases, -orientation, -texture, and -strain/stress. Typically achieved strain resolution is in the order of 5×10−5 strain units. Accurate sample positioning in the x-ray focus spot is achieved with a commercial laser-triangulation unit. A Si-drift detector serves as a high-energy-resolution (∼150 eV full width at half maximum) fluorescence detector. Fluorescence scans can be collected in continuous scan mode with up to 300 pixels/s scan speed. A charge coupled device area detector is utilized as diffraction detector. Diffraction can be performed in reflecting or transmitting geometry. Diffraction data are processed using XMAS, an in-house written software package for Laue and monochromatic microdiffraction analysis.

Graphitic deposits anti‐segregate into Ni⁰ nanoparticles to provide restored CH₄ adsorption sites and near‐surface/dissolved C atoms, which migrate to the Ni⁰/ZrO₂ interface and induce local Zr_xC_y formation. The resulting oxygen‐deficient carbidic phase boundary sites assist in the kinetically enhanced CO₂ activation toward CO(g). This interface carbide mechanism allows for enhanced spillover of carbon to the ZrO₂ support, and represents an alternative catalyst regeneration pathway with respect to the reverse oxygen spillover on Ni‐CeZr_xO_y catalysts. It is therefore rather likely on supports with limited oxygen storage/exchange kinetics but significant carbothermal reducibility.

The success of solid-state synthesis often hinges on the first intermediate phase that forms, which determines the remaining driving force to produce the desired target material. Recent work suggests that when reaction energies are large, thermodynamics primarily dictates the initial product formed, regardless of reactant stoichiometry. Here, we validate this principle and quantify its constraints by performing in situ characterization on 37 pairs of reactants. These experiments reveal a threshold for thermodynamic control in solid-state reactions, whereby initial product formation can be predicted when its driving force exceeds that of all other competing phases by ≥60 milli–electron volt per atom. In contrast, when multiple phases have a comparable driving force to form, the initial product is more often determined by kinetic factors. Analysis of the Materials Project data shows that 15% of possible reactions fall within the regime of thermodynamic control, highlighting the opportunity to predict synthesis pathways from first principles.

The more than a century-old technique of X-ray diffraction in either angle or energy dispersive mode has been used to probe materials’ microstructure in a number of ways, including phase identification, stress measurements, structure solutions, and the determination of physical properties such as compressibility and phase transition boundaries. The study of high-pressure and high-temperature materials has strongly benefitted from this technique when combined with the high brilliance source provided by third generation synchrotron facilities, such as the Advanced Light Source (ALS) (Berkeley, CA, USA). Here we present a brief review of recent work at this facility in the field of X-ray diffraction under extreme conditions, including an overview of diamond anvil cells, X-ray diffraction, and a summary of three beamline capabilities conducting X-ray diffraction high-pressure research in the diamond anvil cell.