Abstracts » Zoology and wildlife conservation

Metallic solid silicon

Article Abstract:

Materials scientists have converted silicon from its ordinary semiconducting or nonmetallic state to a metallic state by imposing a diamond pyramid under load onto small plastic indentations formed in pure silicon crystals. This achievement, brought about by the combined efforts of a series of researchers, may presage a significant new advance in materials science. The observation that an amorphous phase resulted from diamond pyramid pressure on silicon crystals was the first step, followed by the discovery of plastic extrusions surrounding nanoindentations in the silicon.

Semiconductors, Silicon

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Superdiffusion in solid helium

Article Abstract:

Emil Polturak and colleagues have concentrated on the mechanical behavior of solid helium and have shown that superdiffusion occurs at the temperature at which solid helium changes crystal structure, and is associated with a stress resistance reduction. They used nuclear magnetic resonance (NMR) and slow plastic flow or creep was observed in single crystals of solid (super4)He and of (super4)He-(super3)He combinations.

Helium

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The how and why of thermal contraction

Article Abstract:

Research on zirconium and and hafnium tungstates provides new information on the phenomenon of thermal contraction. The two isomorphous crystals consist of ZrO6 or HfO6 octahedra linked through oxygen atoms to WO4 tetrahedra, leaving one unlinked oxygen on each tetrahedron. During thermal contraction, the polyhedra librate in a coupled manner via transverse vibrations resulting in a shortening of Zr-O-W bonds.

Crystals, Thermal properties

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