Minelli, A. | Search NASA

DOE OSTI2024

Unravelling Disorder in Aperiodic Crystals – Diffuse Scattering and Atomic Resolution Holography

The atomic–scale disorder of aperiodic crystals, and quasicrystals in particular, is inherently difficult to explore by experimental methods due to their complex atomic arrangements. Two advanced characterization techniques, a revived and an emerging one, offer direct experimental access even to such complex atomic structures: Diffuse Scattering and Atomic Resolution Holography. Finally, in this overview, we introduce their specific application to aperiodic crystals and discuss their merits and difficulties.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

DOE OSTI2019

Lattice dynamics and phase stability of rhombohedral antimony under high pressure

The high pressure lattice dynamics of rhombohedral antimony have been studied by a combination of diffuse scattering and inelastic x-ray scattering. The evolution of the phonon behavior as a function of pressure was analyzed by means of two theoretical approaches: density functional perturbation theory and symmetry-based phenomenological phase transition analysis. Here, this paper focuses on the first structural phase transition, SbI-SbIV, and the role of vibrations in leading the transition. The phonon dispersion exhibits complex behavior as one approaches the structural transition, with the branches, corresponding to the two transitions happening at high pressure in the Va elements (A7-to-BCC and A7-to-PC) both showing softening.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗