ausblenden:
Schlagwörter:
high pressure, high temperature, phase transformation, microstructure analysis, X-ray diffraction,
transmission electron microscopy
Zusammenfassung:
Among the microstructure defects in hexagonal graphitic boron nitride, the basal plane corrugations
are of high relevance for the sp2 to sp3 phase transition under high pressures (HP) and high temper-
atures (HT). A microstructure model is described, which is capable of quantifying the amplitude of the
basal plane corrugations on the basis of the anisotropic X-ray diffraction line broadening. It is illus-
trated that this model correctly reproduces the specific shape of the diffraction lines from corrugated
basal planes, i.e., the characteristic splitting of the 00l peaks. The results from XRD are verified by
direct observation in the transmission electron microscope with high resolution. Subsequent HP/
HT experiments were performed in order to highlight the difference in the phase transition kinetics
between hexagonal boron nitride samples with different amount of basal plane corrugations. The ef-
fect of these microstructure defects on the conversion rate and on the obtained synthesis product is
discussed.
