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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.

ZnO and ZnS powders were prepared from aqueous solutions of zinc salts in the presence of ethylenediamine or triethanolamine. The morphology of the powders was analysed by scanning electron microscopy and infrared spectroscopy. The effect of the experimental conditions upon the size and shape of the particles is described with a special emphasis on the role of the organic ligand.

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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Cadmium sulfide and cadmium selenide nanoparticles have been synthesised by a novel route involving the thermal decomposition of the bisdiethyldithio-or bisdiethyldiseleno-carbamates of cadmium in refluxing 4-ethylpyridine solutions. The nanodispersed materials were studied by electronic spectroscopy and bandgaps were blue shifted. Transmission electron microscopy of the samples showed material to be in the nanosize range and crystalline.There has been considerable interest in the synthesis and characterisation of semiconductor nanoparticle~.'-~ Nanoparticles, also known as nanocrystallites, Q-particles or quantum dots, are particles with a high surface : volume ratio and diameters of up to 10-20 nm, their opto-electronic properties are different from the bulk counterparts, and new technological applications have been proposed for this type ofThe prospects for devices are now more immediate and a number of recent papers have reported on either the photoluminescent properties of nanodispersed II-VI materials' or photoluminescent devices based on such II-VI materiakg Nanoparticles are also important in fundamental research because they represent a state of matter in which the transition from molecular to the bulk (macrocrystalline) level can be investigated e~perimentally.'-~The preparations of nanoparticles of many semiconductors have been reported, these include: PbS,lo,l' CdS,',1'-'6 CdSe,16-'9 CdTe,16 ZnS,20-22 ZnO,', Ti02,24 InP,25 G~A s , '~. '~ Zn3PZ2' and Cd3P2.20*21 More recently, the synthesis of nanocomposites has been subject of intense research as well. Some examples of nanocomposite materials described in the literature are ZnS/CdSe," CdS/PbS,'1*2' SiO,/CdSZ9 and CdS/ZnS.30 There are other reports of studies concerning the preparation of nanoparticulate systems including elemental Ag,31 Ge,32 Pd33 and Pt34 or metal halides such as HgIZ3 ' and PbI,.36 Theoretical models predicting the optical properties of semiconductor nanoparticles are a~ailable,~-~' but the properties of nanoparticles obtained by any new synthetic procedure are hard to anticipate. The following characteristics are desirable in the final nanodispersed system: high purity, monodispersity and an ability to control surface derivatization. Nanoparticles with these properties have been prepared by several synthetic methods and/or separation technique^. the one-step preparations of nanoparticles containing those elements. Such an approach avoids the use of toxic and pyrophoric compounds such as Cd( CH,), , which is commonly used for preparing nanodispersed cadmium chalcogens. l6 Solid cadmium diethyldithiocarbamate (Cddtc) and cadmium diethyldiselenocarbamate (Cddsc) are dimeric compounds of molecular formula (Cd [E,CN(C,H,),], ), (E = S, Se). Their crystal structures have been r e p~r t e d~' ,~~ and show distorted square-pyramidal coordination at the metal. The bisdiethyldithio-or bisdiethyldiseleno-carbamates of cadmium have been used in chemical vapour deposition experiments to prepare II-VI semiconductor film^.^',^^ In this work, s...

Research on inorganic/organic nanocomposite materials is a fast growing interdisciplinary area in materials science and engineering. In particular, extensive work has been undertaken in the development of sustainable and environmentally friendly resources and methods. A key idea has been the production of nanocomposites comprising biopolymers that in specific contexts can replace conventional materials such as synthetic polymers. It is well known that the properties of nanocomposite materials depend not only on the properties of their individual components but also on morphological and interfacial characteristics arising from the combination of distinct materials [1]. Therefore the use of polymers such as cellulose, starch, alginate, dextran, carrageenan, and chitosan among others, gain great relevance not only due to their renewable nature and biodegradability, but also because a variety of formulations can be exploited depending on the envisaged functionality [2, 3]. This chapter has focus on the use of cellulose as the matrix in the production of nanocomposites. Cellulose has critical importance namely because is the most abundant and widespread biopolymer on Earth. Owing to its abundance and specific properties, it is important noted for the development of environmental friendly, biocompatible, and functional composites, quite apart from its traditional and massive use in papermaking and cotton textiles [4]. Additionally different types of cellulose are available for the preparation of nanocomposites, namely vegetable cellulose (VC), bacterial cellulose (BC) and nanofibrillated cellulose (NFC). Although sharing similar chemistry and molecular structure, the different kinds of cellulose show important differences in terms of morphology and mechanical behavior. For example, BC and NFC are composed of fibers with nanosized dimensions as compared to VC, which might impart new properties, and in some cases improvements to the ensuing nanocomposite materials [5].

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