منابع مشابه
Novel superhard B-C-O phases predicted from first principles.
We explored the B-C-O system at pressures in the range 0-50 GPa by ab initio variable-composition evolutionary simulations in the hope of discovering new stable superhard materials. A new tetragonal thermodynamically stable phase B4CO4, space group I4[combining macron], and two low-enthalpy metastable compounds (B6C2O5, B2CO2) have been discovered. Computed phonons and elastic constants show th...
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Superhard substances are those a hardness above 20 GPa, i.e. higher than that of corundum (Kislii et al.,1988) or with a Vickers hardness Hv exceeding 40 GPa (Sologenko&Gregorianz, 2005). The ten utmost non-metal substances and refractory compounds form a "hardness pyramid" (Kislii et al.,1988) diamond being on top, followed by cubic-boron nitride and boron carbide. Metal-like ones form a simil...
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Using the particle swarm optimization technique, we proposed a cubic superhard phase of C₃N (c-C₃N) with an estimated Vicker's hardness of 65 GPa, which is more energetically favorable than the recently proposed o-C₃N. The c-C₃N is the most stable phase in a pressure range of 6.5-15.4 GPa. Above 15.4 GPa, the most energetic favorable high pressure phase R3m-C₃N is uncovered. Phonon dispersion a...
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Dynamic data, cache, and memory adaptation can significantly improve program performance when they are applied on long continuous phases of execution that have dynamic but predictable locality. To support phased-based adaptation, this paper defines the concept of locality phases and describes a four-component analysis technique. Locality-based phase detection uses locality analysis and signal p...
متن کاملRhombohedral superhard structure of BC2N
Ab initio evolutionary algorithm was employed to resolve the crystal structure of the observed superhard BC2N. We uncovered two polymorphs with rhombohedral 2 f.u./cell and orthorhombic 2 f.u./cell symmetries, with which the experimental x-ray diffraction pattern is well reproduced. Analysis of the total energy results and the simulated energy-loss near-edge spectroscopy suggests that the rhomb...
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ژورنال
عنوان ژورنال: Journal of Superhard Materials
سال: 2010
ISSN: 1063-4576,1934-9408
DOI: 10.3103/s1063457610030056