Charge transfer in spinel Co3O4 at high pressures.

Charge transfer in cobalt oxide Co(3)O(4) in the spinel structure is evidenced by experimental results using x-ray diffraction (XRD), x-ray absorption near edge structure (XANES) spectroscopy, and Raman scattering at high pressures up to 42.1, 24.6 and 35.

Origin of pressure-induced polyamorphism in Ce75Al25 metallic glass.

Using high-pressure synchrotron x-ray absorption spectroscopy, we observed the Ce 4f electron in Ce(75)Al(25) metallic glass transform from its ambient localized state to an itinerant state above 5 GPa. A parallel x-ray diffraction study revealed a volume collapse of about 8.6%, coinciding with 4f delocalization.

Substitutional alloy of Ce and Al.

The formation of substitutional alloys has been restricted to elements with similar atomic radii and electronegativity. Using high-pressure at 298 K, we synthesized a face-centered cubic disordered alloy of highly dissimilar elements (large Ce and small Al atoms) by compressing the Ce(3)Al intermetallic compound >15 GPa or the Ce(3)Al metallic glass >25 GPa. Synchrotron X-ray diffraction, Ce L(3)-edge absorption spectroscopy, and ab initio calculations revealed that the pressure-induced Kondo volume collapse and 4f electron delocalization of Ce reduced the differences between Ce and Al and brought them within the Hume-Rothery (HR) limit for substitutional alloying.