Micelles methods

Nanoparticles of Mn and Pr-doped ZnS and CdS-ZnS were synthesized by wrt chemical method and inverse micelle method. Physical and fluorescent properties wra cbaractmzed by X-ray diffraction (XRD) and photoluminescence (PL). ZnS nanopatlicles aniKaled optically in air shows higher PL intensity than in vacuum. PL intensity of Mn and Pr-doped ZnS nanoparticles was enhanced by the photo-oxidation and the diffusion of luminescent ion. The prepared CdS nanoparticles show cubic or hexagonal phase, depending on synthesis conditions. Core-shell nanoparticles rahanced PL intensity by passivation. The interfacial state between CdS core and shell material was unchan d by different surface treatment. 

CdS and CdS-ZnS core-shell nanoparticles were synthesized by inverse micelle method. Crystallinity of CdS nanoparticles was hexagonal structure under the same molar ratio of CM and S precursor. However it was changed easily to cubic structure under the condition of sonication or higher concentration of Cd than S precursor. The interfacial state betwran CdS core and shell material was unchanged by different surface treatment. 

Figure 5. Synthetic steps for preparation of monodispersed Au nanoparticles by the inverse micelle method and digestive ripening.

Figure 9. TEM micrographs of nanocrystal superlattices of Au nanoparticles prepared by the inverse micelle method and digestive ripening, (a) and (b) low-magnification images (c (f) regularly-shaped nanocrystal superlattices (g) magnified image of a superlattice edge. Note the perfect arrangement of the Au nanoparticles. (Reprinted with permission from Ref. [30], 2003, American Chemical Society.)...

Figure 17. Different steps involved in the digestive ripening procedure of colloids prepared by the inverse micelle method.

FIGURE 1.2. Formation of nanoparticles of metal oxide by reverse micelle method. A solution of inverse micelles is first formed by adding a long-chain alkylamine to a toluene solution. A small amount of water is trapped in the reverse micelle core. Mixing the reverse micelle solution with an aluminum alkoxy amine adduct results in hydrolysis of the aluminum alkoxide adduct and formation of nano-sized particles of aluminum oxyhydroxide after drying. These particles are shown in the SEM picture above. 

Kim D, Miyamoto M, Nakayama M (2005) Photoluminescence properties of CdS and CdMnS quantum dots prepared by a reverse-micelle method. J Electron Microsc 54 131-134... 

Zhang J, Sun LD, Liao CS, Yan CH (2002) Size control and photoluminescence enhancement of CdS nanoparticles prepared via reverse micelle method. Solid State Commun 124 45-48... 

Many approaches have been taken to prepare colloidal doped semiconductor nanocrystals. For example, hot-injection methods have been used to synthesize colloidal Mn2+-doped CdSe (47, 48), ZnSe (49), and PbSe (50) colloidal nanocrystals. Colloidal ZnO DMS-QDs doped with Co2+, Ni2+, and Mn2+ have been prepared by low-temperature hydrolysis and condensation (51-54). Sol-gel methods have been used to prepare colloidal doped TiC>2 (55-57) and Sn02 (58-62) nanocrystals. Inverted micelle methods have been used for preparation of a range of doped II-VI sulfide DMS-QDs at low temperatures (63-68). A high-temperature lyothermal single-source method was used to synthesize Co2+- and Eu3+-doped CdSe nanocrystals (69, 70). Autoclaving has occasionally been used to induce crystallization at lower temperatures than reached under atmospheric pressures while retaining colloidal properties, for... 

A deeper understanding of the chemistry from Fig. 8 is obtained by closer inspection of the final products. Figure 9(a) shows a set of absorption spectra (68) collected on Co2+ CdS QDs prepared by the same inverted micelle method and resuspended in Py. Over time, the Co2+ ligand-field absorption intensity... 

T. Yamaki, H. Maeda, K. Kusakabe and S. Morooka, Control of the pore characteristics of thin alumina membranes with ultrafine zirconia particles prepared by the reversed micelle method. /. Membr. Sci., 85 (1993) 167. 

Kida, I. . Guan. G.. Minami, Y, Ma, T., and Yoshida, A. 2003. Photocatalytic hydrogen production from water over a LaMnO,/CdS composite prepared by the reverse micelle method. Journal of Materials Chemistry 13, 1186-1191. 

Kinoshita, T., Seino, S., Okitsu, K., Nakayama, T., Nakagawa, T. and Yamamoto, I. A. (2003) Magnetic evaluation of nanostructure of gold-iron composite particles synthesized by a reverse micelle method. /. Alloys Compd., 359, 46-50. 

Han, M., Vestal, C.R. and Zhang, Z.J. (2004) Quantum couplings and magnetic properties of CoCrxFe2-x04 (0 < x < 1) spinel ferrite nanoparticles synthesized with reverse micelle method. /. Phys. Chem. B, 108, 583-597. 

The kinetics of formation and disintegration of micelles has been studied for about thirty years [106-130] mainly by means of special experimental methods, which have been proposed for investigation of fast chemical reaction in liquids [131]. Most of the experimental methods for micellar solutions study the relaxation of small perturbations of the aggregation equilibrium in the system. Small perturbations of the micellar concentration can be generated by either fast mixing of two solutions when one of them does not contain micelles (method of stopped flow [112]), or by a sudden shift of the equilibrium by instantaneous changes of the temperature (temperature jump method [108, 124, 129, 130]) or pressure (pressure jump method [1, 107, 116, 122, 126]). The shift of the equilibrium can be induced also by periodic compressions or expansions of a liquid element caused by ultrasound (methods of ultrasound spectrometry [109-111, 121, 125, 127]). All experimental techniques can be described by the term relaxation spectrometry [132] and are characterised by small deviations from equilibrium. Therefore, linearised equations can be used to describe various processes in the system. 

The UV-vis spectra of zinc sulfide colloidal dispersions are characterized by narrow maximum at 280 nm. Changing the precursor concentration from 0.01 M to 0.05 M results in the little (about 5 nm) red shift and the evidence of the size increase. The similar phenomenon was observed in the case of CdS nanoparticles prepared via the reverse micelle method [9]. For ZnS nanoparticles, the band gap (280 nm) shifts towards the blue region with respect to ZnS bulk semiconductor (350 nm) which is ascribed to the quantum... 

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