A range of bismuth(III) dithiocarbamato complexes were prepared and characterized. The X-ray crystal structures of the compounds [Bi{S 2 CN(CH 3 )(C 6 H 13 )} 3 ] (1) and [Bi{S 2 CN(CH 3 )-(C 6 H 13 )} 3 (C 12 H 8 N 2 )] (2) are reported. The preparation of Bi 2 S 3 particulates using a wet chemical method and involving the thermalysis of Bi(III) dialkyldithiocarbamato complexes is described. The influence of several experimental parameters on the optical and morphological properties of the Bi 2 S 3 powders was investigated. Nanosized Bi 2 S 3 colloids were obtained having long-term stability and showing a blue shift on the optical band edge; the presence of particles exhibiting quantum size effects is discussed. Morphological welldefined Bi 2 S 3 particles were obtained in which the fiber-type morphology is prevalent.

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phases, than that in the hydrogen/BN systems. However, the similar HOMO±LUMO difference in all CH x /BN systems reveals no etching selectivity by CH x for the two BN phases. To reconcile the discrepancy, we suggest that the introduction of CH x probably results in the attachment of CH x to the BN phases. Calculations on two BN clusters saturated with CH 3 species have shown an obvious disparity between the HOMO±LUMO differences for H/h-BN-CH 3 , and those for H/c-BN-CH 3 systems. The results reveal the etching selectivity of hydrogen with the addition of methyl species, in the boron nitride deposition, which is consistent with the observation of Harris et al. [8] Results from the studies of the hydrogen anion interacting with BN or C systems are shown in Figure 3b. Compared to the neutral hydrogen species, higher reactivities are predicted for the hydrogen anion. The etching selectivity for BN and C phases of the hydrogen anion is similar to that of the neutral hydrogen species. However, it should be noted that, during the interaction of hydrogen ions with the BN or C clusters, charge transfer might take place. This would lead to neutralization of the hydrogen ion, and charging of the substrate. The reactivity between the neutralized hydrogen atom and the charged clusters was, therefore, studied further. Again, the results predict a higher reactivity than that of the neutral hydrogen species/neutral C or BN cluster systems. This shows that charge transfer does not affect conclusions based on calculations using the hydrogen anion and neutral clusters.To date, no high-quality, single-phase BN films have been successfully synthesized by CVD techniques. One possible reason is the absence of selective etchants for the two BN phases in the CVD process. Contrary to the expectation that hydrogen species would be a selective etchant as in CVD diamond growth, we have shown that they do not selectively etch the sp 2 phase in BN growth. Our results suggest that, instead of finding a selective sp 2 etching agent for BN phases, the successful CVD synthesis of single-phase BN films may be better achieved by promoting the formation of the sp 3 phase. Toward this end, a new, effective sp 3 phase BN promoter and/or a species preventing the formation of sp 2 phase BN should be sought.

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