100 research outputs found
Process for ultra smooth diamond coating on metals and uses thereof
The present invention provides a new process to deposit well adhered ultra smooth diamond films on metals by adding nitrogen gas to the methane/hydrogen plasma created by a microwave discharge. Such diamond coating process is useful in tribological/wear resistant applications in bio-implants, machine tools, and magnetic recording industry
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Development of Designer Diamond Technology for High Pressure High Temperature Experiments in Support of Stockpile Stewardship Program
The role of nitrogen in the fabrication of designer diamond was systematically investigated by adding controlled amount of nitrogen in hydrogen/methane/oxygen plasma. This has led to a successful recipe for reproducible fabrication of designer diamond anvils for high-pressure high-temperature research in support of stockpile stewardship program. In the three-year support period, several designer diamonds fabricated with this new growth chemistry were utilized in high-pressure experiments at UAB and Lawrence Livermore National Laboratory. The designer diamond anvils were utilized in high-pressure studies on heavy rare earth metals, high pressure melting studies on metals, and electrical resistance measurements on iron-based layered superconductors under high pressures. The growth chemistry developed under NNSA support can be adapted for commercial production of designer diamonds
Simultaneous measurement of pressure evolution of crystal structure and superconductivity in FeSe0.92 using designer diamonds
Simultaneous high pressure x-ray diffraction and electrical resistance
measurements have been carried out on a PbO type {\alpha}-FeSe0.92 compound to
a pressure of 44 GPa and temperatures down to 4 K using designer diamond anvils
at synchrotron source. At ambient temperature, a structural phase transition
from a tetragonal (P4/nmm) phase to an orthorhombic (Pbnm) phase is observed at
11 GPa and the Pbnm phase persists up to 74 GPa. The superconducting transition
temperature (TC) increases rapidly with pressure reaching a maximum of ~28 K at
~ 6 GPa and decreases at higher pressures, disappearing completely at 14.6 GPa.
Simultaneous pressure-dependent x-ray diffraction and resistance measurements
at low temperatures show superconductivity only in a low pressure orthorhombic
(Cmma) phase of the {\alpha}-FeSe0.92. Upon increasing pressure at 10 K near
TC, crystalline phases change from a mixture of orthorhombic (Cmma) and
hexagonal (P63/mmc) to a high pressure orthorhombic (Pbnm) phase near 6.4 GPa
where TC is maximum.Comment: 6 figures, 6 pages, Subjects: Superconductivity and Condensed matter
(structural, mechanical & thermal
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