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1.
Composite diamond anvils have been developed for high-pressure/high-temperature measurements of diamond anvil cells. The anvils are fabricated using single-crystal chemical vapor deposition (CVD) from previously used and/or slightly damaged anvils made of natural or synthetic diamond. These composite anvils can be fabricated to possess optical characteristics at least comparable to conventional diamond anvils, whereas the single-crystal CVD portion is more durable because of its enhanced toughness relative to natural diamond. The viability of such anvils is demonstrated in measurements on hydrogen at megabar pressures and high temperature.  相似文献   
2.
Conclusions A method is proposed for the reduction of laminar graphite compounds at hydrogen pressure up to 70 kbar, which has a number of significant advantages relative to reported methods. This method may be used to obtain new acceptor LGC.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 2, pp. 450–452, February, 1986.The authors express their gratitude to P. B. Fabrichnyi for assistance in the Moessbauer spectral study of these compounds.  相似文献   
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Cubic zinc oxide (rs-ZnO), metastable under normal conditions, was synthesized from the wurtzite modification (w-ZnO) at 7.7 GPa and ∼800 K in the form of nanoparticles isolated in the NaCl matrix. The phase transition rs-ZnO → w-ZnO in nanocrystalline zinc oxide under ambient pressure was experimentally studied for the first time by using differential scanning calorimetry and high-temperature X-ray diffraction analysis. It was shown that the transition occurs in the temperature range from 370 to 430 K and its enthalpy at 400 K is −10.2 ± 0.5 kJ mol−1.  相似文献   
5.
Kinetics of the wurtzite-to-rock-salt transformation in ZnO has been studied in the 5-7 GPa pressure range at temperatures below the activation of diffusion processes. The detailed analysis of non-isothermal experimental data using the general evolution equation describing the kinetics of direct phase transformations in solids allowed us to study the kinetic particularities of both nucleation and growth of the rock-salt phase in parent wurtzite ZnO. The main rate-limiting processes are thermally activated nucleation (E(N) = 383 kJ mol(-1) at 6.9 GPa) and thermally nonactivated (most probably quasi-martensitic) growth (k(G) = 0.833 min(-1) at 6.9 GPa). The high impact of thermal deactivation of nucleation places has been evidenced in the case of slow heating, which indirectly indicates that the rs-ZnO nucleation places are mainly produced by pressure-induced stresses in the parent phase.  相似文献   
6.
The four 5v 3 bands of 18O enriched ozone have been observed and analysed for the first time. Two species (16O18O16O and 18O16O18O) belong to the C2v symmetry group and two other (18O18O16O and 16O16O18O) to the Cs symmetry group. They have been recorded at a resolution of 0.008 cm?1 with a pathlength of 32.16 m. Despite the very weak absorptions observed, almost 250 energy levels have been derived for each of the 4 species, with J ? 35 and K a ? 13, and suitable sets of Hamiltonian parameters have been determined. For 3 species it has been necessary to account for the resonance between the (005) and (311) states to correctly reproduce the spectra observed. These resonances, anharmonic for C2v, and hybrid (both anhar-monic and Coriolis) for Cs symmetry confirm the accidentally extremely strong coupling between the (005) and (311) states for 16O3, due in that case to the very close distance between unperturbed energy levels. This work also confirms the excellent prediction of band centres of these four species derived from the recently determined isotopically invariant molecular potential function.  相似文献   
7.

Novel ternary diamond-like phases of the B-C-N system were synthesized at pressures up to 30 GPa and temperatures up to 3500 K by static and dynamic compression of graphite-like BN-C solid solutions. Structure and properties of these new phases were studied using X-ray diffraction with synchrotron radiation, analytical transmission electron microscopy (ATEM), electron energy loss spectroscopy (EELS), microhardness measurements and nanoindentation.  相似文献   
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The lattice parameters of Al3BC have been measured up to 5 GPa at ambient temperature using energy-dispersive X-ray powder diffraction with synchrotron radiation. A fit to the experimental p-V data using Birch-Murnaghan equation of state gives values of the Al3BC bulk modulus 116(4) GPa and its first pressure derivative 9(2). In the 1.6-4.8 GPa range at temperatures above 1700 K Al3BC undergoes incongruent melting that results in the formation of Al3BC3, AlB2 and liquid aluminum.  相似文献   
10.
The polymorphic transformations of wurtzitic modification of boron nitride into graphite-like ones have been studied using DSC, inverse drop-calorimetry and dilatometry over the temperature range of 500 to 1400 K. The transformation enthalpies at 1380 K were determined to be +14±2 kJ/mole and +17±3 kJ/mole for wBN→hBN and wBN→rBN transformations, respectively.
Zusammenfassung Mittels DSC, inverser Dropkalorimetrie und Dilatometrie im Temperaturbereich von 500 bis 1400 K wurden die polymorphen Umwandlungen der Wurtzit-Modifikation von Bornitrid in die Graphit-Modifikation untersucht. Die Umwandlungsenthalpien bei 1380 K für die Umwandlungen wBN→hBN und wBN→rBN wurden mit +14±2 kJ/mol und mit +17±3 kJ/mol bestimmt.
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