Ultrafine-grained, nanophase samples of TiO2 (rutile) were synthesized by the gas-condensation method and subsequent in situ compaction. The samples were studied by a number of techniques, including transmission electron microscopy, Vickers microharness measurements, and positron annihilation spectroscopy, as a function of sintering temperature. The nanophase compacts with average initial grain sizes of 12 nm were found to densify rapidly above 500 °C, with only a small increase in grain size. The hardness values obtained by this method are comparable to or greater than those for coarser-grained compacts, but are achieved at temperatures 400 to 600 °C lower than conventional sintering temperatures and without the need for sintering aids.
We have functionalized poly(N-vinyl carbazole) (PVK) by controlled sulfonation. CdS nanocystals of 3−20
nm across were synthesized in the sulfonated PVK matrix with the CdS molar fraction of ∼1−18%. The
CdS nanoparticle size increased with the molar fraction of CdS. At high CdS molar fractions, the CdS
nanocrystals exist in both cubic and hexagonal phases. Photoluminescence efficiency of PVK decreases when
the molar fraction of CdS increases due to quenching through interfacial charge transfer. Photoluminescence
attributable to the CdS nanocrystals can be observed only at low molar fractions of CdS. Significant
enhancement in photoconductivity induced by the chemical doping of CdS in PVK has also been demonstrated.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.