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Shape and phase control of CdS nanocrystals using cationic surfactant in noninjection synthesis.

Zou Y, Li D, Yang D - Nanoscale Res Lett (2011)

Bottom Line: Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system.With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite.In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China. mselds@zju.edu.cn.

ABSTRACT
Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system. With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite. It was found that halide ion Cl- plays a key role in the transformation, and other halide ions such as Br- can also induce similar transformation. We proposed that the strong binding between Cd2+ and halide ions reduced the reactivity of the precursors, decreased the nuclei formed in the nucleation stage, and led to the high concentration of precursor in the growth stage, resulting in the increase of size and phase transformation of CdS nanocrystals. In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

No MeSH data available.


Related in: MedlinePlus

HRTEM images of the multi-armed CdS nanocrystals synthesized with 0.5 mmol CTAC added: (a) HRTEM image of a typical CdS bipod, consisting of a zinc-blende core and two wurtzite arms; (b) HRTEM image of a CdS tetrapod viewed along the [111] direction of the zinc-blende core.
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Figure 3: HRTEM images of the multi-armed CdS nanocrystals synthesized with 0.5 mmol CTAC added: (a) HRTEM image of a typical CdS bipod, consisting of a zinc-blende core and two wurtzite arms; (b) HRTEM image of a CdS tetrapod viewed along the [111] direction of the zinc-blende core.

Mentions: For a more detailed structural characterization of the multi-armed CdS nanocrystals, HRTEM images of the sample with 0.5 mmol CTAC added were recorded. Figure 3a shows a typical HRTEM image of a single CdS bipod. It is obvious that the CdS bipod consists of a zinc-blende core with two wurtzite arms grown out of the (111) facets of the zinc-blende core. The wurtzite arms grow along the [0001] direction which is also confirmed by the cross-sectional image shown in Figure 3b. Figure 3b shows the typical HRTEM image of a CdS tetrapod which is viewed along the [111] direction of the zinc-blende core. It is seen that the cross-sectional plane of the wurtzite arm is that of (0001) which fits well with the (111) plane of the zinc-blende core. From these observations, the crystal nature of the multi-armed CdS nanocrystals is the same as that of other nanotetrapods reported in the literature [22-26]. The formation of the CdS multi-armed nanocrystals is the result of nucleation of zinc-blende cores followed by surface-initiated growth of wurtzite arms. The low yield of tetrapods in the product mixture is probably attributed to the low precursor concentration in the reaction mixture [14,15].


Shape and phase control of CdS nanocrystals using cationic surfactant in noninjection synthesis.

Zou Y, Li D, Yang D - Nanoscale Res Lett (2011)

HRTEM images of the multi-armed CdS nanocrystals synthesized with 0.5 mmol CTAC added: (a) HRTEM image of a typical CdS bipod, consisting of a zinc-blende core and two wurtzite arms; (b) HRTEM image of a CdS tetrapod viewed along the [111] direction of the zinc-blende core.
© Copyright Policy - open-access
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC3211467&req=5

Figure 3: HRTEM images of the multi-armed CdS nanocrystals synthesized with 0.5 mmol CTAC added: (a) HRTEM image of a typical CdS bipod, consisting of a zinc-blende core and two wurtzite arms; (b) HRTEM image of a CdS tetrapod viewed along the [111] direction of the zinc-blende core.
Mentions: For a more detailed structural characterization of the multi-armed CdS nanocrystals, HRTEM images of the sample with 0.5 mmol CTAC added were recorded. Figure 3a shows a typical HRTEM image of a single CdS bipod. It is obvious that the CdS bipod consists of a zinc-blende core with two wurtzite arms grown out of the (111) facets of the zinc-blende core. The wurtzite arms grow along the [0001] direction which is also confirmed by the cross-sectional image shown in Figure 3b. Figure 3b shows the typical HRTEM image of a CdS tetrapod which is viewed along the [111] direction of the zinc-blende core. It is seen that the cross-sectional plane of the wurtzite arm is that of (0001) which fits well with the (111) plane of the zinc-blende core. From these observations, the crystal nature of the multi-armed CdS nanocrystals is the same as that of other nanotetrapods reported in the literature [22-26]. The formation of the CdS multi-armed nanocrystals is the result of nucleation of zinc-blende cores followed by surface-initiated growth of wurtzite arms. The low yield of tetrapods in the product mixture is probably attributed to the low precursor concentration in the reaction mixture [14,15].

Bottom Line: Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system.With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite.In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

View Article: PubMed Central - HTML - PubMed

Affiliation: State Key Laboratory of Silicon Materials and Department of Materials Science and Engineering, Zhejiang University, Hangzhou 310027, People's Republic of China. mselds@zju.edu.cn.

ABSTRACT
Monodispersed CdS nanocrystals with controllable shape and phase have been successfully synthesized in this study by adding cationic surfactant in noninjection synthesis system. With the increase of the amount of cetyltrimethylammonium chloride (CTAC) added, the shape of the CdS nanocrystals changed from spherical to multi-armed, and the phase changed from zinc-blende to wurtzite. It was found that halide ion Cl- plays a key role in the transformation, and other halide ions such as Br- can also induce similar transformation. We proposed that the strong binding between Cd2+ and halide ions reduced the reactivity of the precursors, decreased the nuclei formed in the nucleation stage, and led to the high concentration of precursor in the growth stage, resulting in the increase of size and phase transformation of CdS nanocrystals. In addition, it was found that the multi-armed CdS nanocrystals lost quantum confinement effect because of the increase of the size with the increase of the concentration of CTAC.

No MeSH data available.


Related in: MedlinePlus