In situ studies of boron nitride crystallization from BN solutions in supercritical N–H fluid at high pressures and temperatures
| Autor: | Mohamed Mezouar, Vladimir Z. Turkevich, Yann Le Godec, Stefan Klotz, Vladimir L. Solozhenko, J. M. Besson |
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| Rok vydání: | 2002 |
| Předmět: |
Materials science
Precipitation (chemistry) Thermal decomposition Intercalation (chemistry) Inorganic chemistry Analytical chemistry General Physics and Astronomy chemistry.chemical_element Supercritical fluid law.invention chemistry.chemical_compound chemistry law Boron nitride Physical and Theoretical Chemistry Crystallization Boron Phase diagram |
| Zdroj: | Phys. Chem. Chem. Phys.. 4:5386-5393 |
| ISSN: | 1463-9084 1463-9076 |
| Popis: | The reaction of boron with products of the thermal decomposition of hydrazine and the crystallization of boron nitride from BN solutions in supercritical N–H fluid have been studies in situ at pressures up to 5.2 GPa and temperatures up to 1600 K using angle- and energy-dispersive X-ray diffraction with synchrotron radiation. Graphite-like boron nitride produced by the reaction between boron and N–H supercritical fluid dissolves in the latter to form associated solutions of different concentrations. On cooling, the disappearance of short-range order in this solution is observed, accompanied by the precipitation of solid phases (cBN or hBN and BN–NH3 intercalation compound depending on the pressure, temperature and concentration). Spontaneous crystallization of cubic boron nitride has been observed down to 1.9 ± 0.2 GPa, which is the lowest pressure of the cBN crystallization from a solution reported so far. The BN–NH3 hypothetical quasibinary section of the phase diagram of the B–N–H system at 4 GPa has been constructed. |
| Databáze: | OpenAIRE |
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