Wang Deqiang

A mineralogical study of diatomite in Leizhou Peninsula

In this paper diatomite samples taken from the Leizhou Peninsula have been studied by chemical analysis, DTA, TG, XRD, IR, SEM and X-ray Energy Spectroscopy. The study shows that the diatomaceous genera and species and their organic contents are variable with buried depth, fromMelosira toStephanodiscus and the toCyclotella. Various impurities in the samples, such as quartz, kaolinite and montmorillonite indicate different sedimentary environments. When heated, the diatom would change in shape due to the phase transformation in which amorphous silica crystallized from disordered opal to ordered cristobalite. The temperatures of phase transformation are different for various diatoms due to the presence of different impurities and constituents of diatomaceous genera and species.

Composition and assemblage characteristics of magnetic minerals in layer S5-1 of Xifeng and Duanjiapo sections

Relatively strongly magnetic fine components (< 30μm, XS-4J and DS-4J) which are most environmentally sensitive were separated from layer S5-1 in the Xifeng and Duanjiapo loess sections and analyzed by MPV-3 for their morphometric characteristics and reflectance, SEM-ESD for their element contents and XRD for their mineral phases, respectively. The results showed that minerals in both samples are dominated by detrial Fe-Ti oxides of aeolian origin. In sample XS-4J the reflectance and iron contents of magnetic minerals are usually high. In addition to magnetite (Fe3O4), maghemite (γFe2O3) and hematite (Fe2O3), some Fe-high oxide (72.25 wt%–86.67 wt%), ilmenite (FeTiO3), and magnetite-ulvöspinel [Fe(FeCr)O4, Fe (FeNi)O4] were also detected. In sample DS-4J obvious negative linear correlations were found between Ti and Fe, and the contents of Mn, Si, Al and Ca are usually high and the minerals are dominated by magnetite (maghemite), goethite (FeOOH) and limonite (containing Si and OH). In addition, the signs of corrosion of magnetic minerals and newly crystallized magnetite (maghemite) were recognized. Differences in the composition and assemblage characteristics of magnetite minerals between XS and DS reflect significant differences in source rocks and preserving conditions.

Controllable synthesis of large scale, catalyst-free, lateral ZnO nanowires network

We report a novel method for large scale catalyst-free zinc oxide nanowires (ZnO NWs) network growth on Si substrate using chemical vapor deposition (CVD). The SiO2 layer of the Si substrate is photoetched to SiO2 square pillar array which works as the growth core of urchin-like ZnO NW lump, and the NWs cross over each other forming an integrated network. This method achieves controlled growth of lateral ZnO NW network and allows the in situ nano device fabrication. Meanwhile, the vapor deposition mechanism is discussed and confirmed by contrast experiments along with different growth conditions, which realizes growth on large size substrate. According to the result of Field Emission Scanning Electron Microscope (FE-SEM), the ZnO NWs are wurtzite hexagonal single-crystalline and the network is intact with massive intersection points.