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High Temperature and High Pressure Synthesis Study of BC3

Author: ZengZhenWu
Tutor: CuiTian
School: Jilin University
Course: Condensed Matter Physics
Keywords: Laser heating High temperature High pressure Raman spectroscopy
CLC: O52
Type: Master's thesis
Year: 2011
Downloads: 54
Quote: 0
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Abstract


After the material has a high temperature under high pressure synthesis of synthetic materials and under conventional conditions do not have the excellent characteristics, such as high hardness, chemical stability, metal, and excellent anti-oxidation characteristics. In these new materials, high temperature and pressure synthesis of superhard multifunctional materials to be placed high hopes. Modern industrial use of two kinds of super-hard materials are diamond and cubic boron nitride, there is a certain lack of use, resulting in the development has been limited. In recent years, Russian and American scientists in the boron-doped diamond discovered the phenomenon of superconductivity, and the theory predicts higher levels of boron-doped diamond has a higher superconducting transition temperature, the other Japanese researchers found that in some metal high temperature superconducting superconducting temperature than the elemental system doped boron doped with other elements, thus superconducting boron-rich system materials become the topics at the forefront of science. Combination of by BCN three elements the binary or ternary material system has always been a hot design and synthesis of superhard materials, researchers in BCN ternary system synthesis of superhard materials in the experiment did not achieve breakthrough, so the design of superhard materials steering boron carbon binary system. Combined with boron-carbon binary system material has a high boron content, it is possible to have a high superconducting temperature, boron-carbon binary superhard superconducting multi-functional materials design and synthesis of new research hotspot. Using a variety of experimental boron-carbon binary material means of high-temperature and high-pressure synthesis of diamond-like boron-carbon compounds such as: d-BC, d-BC 1.6 . Tetragonal boron-carbon compound c-BC 5 , boron-carbon materials research is a very successful example. Theoretical calculation shows that it is having a high Vickers hardness (71GPa) and a large body modulus (335GPa) semiconductor material, and its thermal stability than the same size diamond to temperature 500K, the structure further up to 45K superconducting transition temperature, high temperature and high pressure experimental techniques is the synthetic boron carbon multifunctional materials preferred. Proportion the already synthesized c-BC in 5 boron element is only 16.7%, but having a superconducting temperature of up to 45K, then the higher amount of boron atoms, the molar ratio of 1:3 the the boron carbon binary system in BC 3 structure type, after high temperature and high pressure processing will also BC 3 new structural materials, super-hard-characteristics and high superconducting transition temperature. In this paper, to produce high-pressure diamond anvil cell, using in situ confocal Raman laser heating of high temperature and high pressure, electron microprobe and other state-of-the-art experimental techniques, the use of graphite-like phase BC 3 for raw materials diamond anvil sample pressurized to 50.5GPa, 40.5GPa, 30.5GPa then laser heating, the heating temperature 1900K ± 20K 1800 ± 20K 1700 ± 20K. 3 samples using high temperature and high pressure in situ Raman scattering experimental techniques, measurement of high temperature and pressure treated BC 3 sample Raman scattering data, found that the graphite-like BC one of the two Raman vibrational modes of the G mode, the peak at 1589cm -1 disappeared, replaced by ten 200-1300cm -1 wavelength range several Raman peak significant change of the Raman peak data show that BC 3 has undergone significant structural phase transition. And currently known boron-carbon compound, boron, carbon, various elemental Raman data were excluded BC 3 sample under high temperature and high pressure decomposition may, identified by the data obtained in the experiment is not currently been the known boron carbon compounds, but a new the BC 3 structure. Diamond anvil successfully synthesized a new atomic structure of BC 3 materials, and this new material can be stable at normal temperature and pressure conditions. Theoretical results contrast with my group of others to determine experimentally synthesized BC 3 has P21 / m symmetry, is a super-hard superconducting properties of multifunctional materials.

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