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Efree

Jamie Molaison, SNS

New high P-T devices for neutron diffraction

Hydrogen-dominated materials will be studied by neutron diffraction at SNS (Oak Ridge). Two new type diamond cells will be developed : a) “belt”-type diamond cell with sample volumes of about ½ mm3 ; b) DAC with modified culets with neutron diffraction capabilities to near 1 Megabar.

"belt"-type large volume diamond cell

 

Terms:

EFree Neutron Science

The national neutron facilities are vital to the core science of the EFree Center. Of particular importance is neutron diffraction, with its unique advantages for characterizing new materials. Unlike x-rays, neutrons are sensitive to the positions of light elements in the vicinity of heavy neighbours, and are also often able to resolve adjacent atoms with similar masses. Furthermore, neutrons are scattered by the nuclei of atoms and, thus, are sensitive to subtle displacements and molecular disorder that are hard to detect with x-rays techniques. This same characteristic also lends itself to structural studies of liquids, glasses, and nano-crystalline materials, which remain challenging even with synchrotron x-ray sources.

SNS Spallation Neutron Source

 

 

 

 

 

 

 

EFree has partnerships with facilities at LANSCE (Los Alamos, NM), SNS and HFIR (Oak Ridge, TN).

The central goal of the EFree Neutron Task Force is to achieve new science in the field of novel materials and properties under extreme conditions. The expertise of Carnegie personnel and partners will be exploited to facilitate the technical developments needed to achieve this goal.

 

Personnel

 

Efree Staff

Malcolm Guthrie (Coordinator)
Xiao-Jia Chen (Neutron Scentist)

Key Partners

Chris Tulk, Spallation Neutron Source (SNS)
Yusheng Zhao, Los Alamos Neutron Science Center (LANSCE)
W. Mao, Stanford University
 

Key Projects

 

 

Terms:

High-Pressure Transformations of Semiconductor Clathrates

Isostructural with hydrate systems are the semiconductor clathrates, which are based on a framework of semiconductor atoms, e.g. Ge and Si, arranged as a host lattice that trap, or enclathrate, metal atoms. Depending on the species and concentration of the guest, these materials show a wide range of functional properties, including semiconducting, metallic and even superconducting behavior.

 

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