Fourier transformation infrared spectrum (FTIR) was employed to investigate phase transformation of nanoparticle BN, containing eBN, rBN, wBN and cBN, in which eBN and rBN are the main components. We found that part of eBN was converted into rBN at 200―350℃. At and above 400℃, eBN transformed into wBN, and some of wBN were converted into cBN simultaneously. This conclusion is supported by the results from high- resolution transmission electron microscopic (HRTEM) and Raman spectroscopic measurements. In this work, the converting processes be- tween different BN phases were continuously monitored by in situ FTIR spectroscopy. The results will be helpful for synthesis of cBN at moderate conditions.
Novel bulk ZnO porous nanosolids were pre- pared by a unique solvothermal hot-press method, using ZnO nanoparticles and several kinds of solvents as the start- ing materials. It was found from the experiments that ZnO nanoparticles underwent a “self-assembly process” under some specific hydrothermal hot-press conditions. As a result, some “nanoflowers” formed. The results showed that porous nanosolids with uniform pore diameters could be obtained when water distributed uniformly among the ZnO nanopar- ticles. On the contrary, if the uniformity of the distribution of water was poor, “nanoflowers” would appear in the wa- ter-rich region. It was also found that the photoluminescence of ZnO porous nanosolids was affected by the self-assembly phenomenon. In addition, the results also showed that, both the volume and diameters of the pores could be adjusted by changing either the hot-press temperature, pressure or the kinds of solvents.
