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Zinc Oxide-Based Nanocomposites for Photocatalytic Conversion of Organic Pollutants in Water
Published in Chaudhery Mustansar Hussain, Ajay Kumar Mishra, Nanocomposites for Pollution Control, 2018
Zinc oxide (ZnO) is an oxidic compound naturally occurring as the rare mineral zincite, which crystallizes in three different structures: wurtzite, zincblende, and rocksalt. It usually appears as a white powder, nearly insoluble in water but soluble in acids and alkalis. ZnO is the most frequently used among the zinc compounds and commercially produced using the French process—the metallic zinc is vaporized in a large container by external heating. In an adjoining off-take pipe or combustion chamber, the vapor is burned off in the air to a fine ZnO powder [1] and American process—oxidized ores of roasted sulfide concentrates are mixed with anthracite coal (carbon additive) and smelted in a furnace. The coal together with the products of partial combustion mainly carbon monoxide reduced the ore to metallic zinc, which is released as vapor. The zinc vapor is then re-oxidized by lower temperature air and formed ZnO particulate. The purity of the ZnO produced by this process is normally rather inferior to that from the French process as it contained low levels of lead and sulfur [1,2].
Electrical and thermal properties of off-stoichiometric SiC prepared by spark plasma sintering
Published in Journal of Asian Ceramic Societies, 2018
Yukina Taki, Mettaya Kitiwan, Hirokazu Katsui, Takashi Goto
Figure 5 shows TEM images of pristine SiC, C-SiC, and Si-SiC. No precipitates of C and Si were observed at the grain boundary and triple points. The added C and Si might be dissolved in a solid solution in the SiC body. Stobierski [15] studied the effect of carbon additive amount on the sintering of SiC and reported that the unreacted C (graphite) precipitated at the grain boundary was found in SiC bodies with the excess of C content of 12 and 23 mol%. In the present study, it was not confirmed whether the 5 mol% of C additive was all dissolved, but a partial amount of the C could be dissolved in the SiC body.