The pressure-volume relationship for cerium monophosphide (CeP) has been determined to 200-kbar pressure. In this range the substance maintains the NaCl-type structure and exhibits abnormal compression. From the data we conclude that there is an electronic transition involving a change in the valence state of Ce from 3 + towards the 4 + state near 100-kbar pressure. Qualitative observations of the reflectivity of CeP under pressure support the valence transition to exhibit superconductivity.
We describe the design, construction, and performance of the MHATT-CAT microdiffraction x-ray monochromator. This monochromator is specially engineered for x-ray microdiffraction experiments with a high brilliance undulator source. The monochromator passes a small emittance beam, suitable for focusing to submicron size with submilliradian divergence. Over its energy range of 8–22 keV the absolute energy calibration is better than 2 eV and scans of ± 1 keV show no measurable hysterisis. The monochromator operates with a simple water-cooled first crystal and shows no measurable warm-up time. Horizontal linear bearings allow the monochromator crystals to be rapidly inserted or removed from the beam. Slits before and after the monochromator work to pass broad bandpass or monochromatic x-ray beams at the same vertical height. The monochromatic beam direction is adjusted so the monochromatic and broad bandpass beams are coaxial. The design and performance of the monochromator allows efficient collection of microdiffraction data when coupled to a nondispersive Kirkpatrick–Baez focusing mirror pair.
The local strain and texture in Al interconnect wires have been investigated using white and monochromatic x-ray microbeams on the MHATTCAT undulator beam line at the Advanced Photon Source. Intergrain and intragrain orientations were obtained with ∼0.01° sensitivity using white beam measurements on wide Al pads (∼100 μm) and thin (2 μm) Al wires. Orientation changes of up to 1°were found within individual grains of the (111) textured Al interconnects. Deviatoric strain measurements indicate small intragranular strain variations, but intergranular strain variations were found to be quite large.
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