Metallic SilaneA. L. Ruoff, Cornell University, DMR-0304745

We have successfully loaded this highly pyrophoric comp-ound into a diamond anvil cell and pressurized it to 218 GPa and made reflectivity and absorption studies. Silane is a compound with a high hydro-gen content and as a metal might be considered a 20 Si – 80 H alloy. Ashcroft has suggested that this metal should be a superconductor at a relatively high temperature [N.W. Ashcroft, Physical Review Letters 92, 187002 (2004)]. We find above 100 GPa a huge jump in reflectivity as the energy decreases. This is character-istic of metallic behavior.

Reflectivity vs energy for Silane at threepressures

1.2 1.4 1.6 1.8 2.0 2.2 2.4 2.6 2.8 3.00.00

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(a): P=110 GPa(b): P=175 GPa(c): P=218 GPa

Ref

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Energy (eV)

Metallic SilaneA. L. Ruoff, Cornell University, DMR-0304745

Education:Both Prof. Liling Sun and Prof. Chandrabhas Narayana learned how to use focused ion beam technology for drilling 5 m holes in the gasket, which will contain the sample. Sun also learned how to work with highly pyrophoric materials such as silane and learned how to load such samples into the diamond anvil cell. An undergraduate class in mechanical properties was taken for a visit of the laboratory to study diamond anvil cell and had homework problems on plastic flow of the gaskets and stress distribution in the diamonds. Dr. Ray Greene learned how to wind the tiny magnetic coils needed for the forthcoming superconducting studies.

Societal Impact:The making and studies of metallic Silane is aimed towards finding a new class of superconductors, which are superconducting to a higher temp-erature than any existing supercond-uctor. This is considered to be a precursor to making and studying metallic hydrogen, which we are actively pursuing.

Birefringence of a diamond stressed to pressure at the earth’s core.