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Morphological variations in cadmium sulfide nanocrystals without phase transformation.

Dhage SR, Colorado HA, Hahn T - Nanoscale Res Lett (2011)

Bottom Line: Environmentally stable and highly crystalline CdS nanorods have been obtained via a chemical bath method.The prepared CdS nanorods have been characterized by X-ray powder diffraction, TEM, UV-Vis spectroscopy, and photoluminescence spectroscopy.The importance of this phenomenon is vital for the potential application for CdS such as smart materials.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical and Aerospace Engineering Department, University of California, Los Angeles, CA 90095, USA. sanjay.dhage@gmail.com.

ABSTRACT
A very novel phenomenon of morphological variations of cadmium sulfide (CdS) nanorods under the transmission electron microscopy (TEM) beam was observed without structural phase transformation. Environmentally stable and highly crystalline CdS nanorods have been obtained via a chemical bath method. The energy of the TEM beam is believed to have a significant influence on CdS nanorods and may melt and transform them into smaller nanowires. Morphological variations without structural phase transformation are confirmed by recording selected area electron diffraction at various stages. The prepared CdS nanorods have been characterized by X-ray powder diffraction, TEM, UV-Vis spectroscopy, and photoluminescence spectroscopy. The importance of this phenomenon is vital for the potential application for CdS such as smart materials.

No MeSH data available.


Related in: MedlinePlus

(a) and (b) TEM image corresponding diffraction pattern of single CdS nanorod; (c) TEM image at beginning of the melting of CdS nanorods; (d) TEM image of almost completely melted nanorods and corresponding diffraction pattern.
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Figure 3: (a) and (b) TEM image corresponding diffraction pattern of single CdS nanorod; (c) TEM image at beginning of the melting of CdS nanorods; (d) TEM image of almost completely melted nanorods and corresponding diffraction pattern.

Mentions: While analyzing the nanorods, the TEM beam current was 80 μA at accelerating voltage of 100 kV. Figure 3a,b shows a TEM image of a single nanorod and a corresponding diffraction pattern, respectively. The SAED pattern can be indexed for the zone axis of (111) single-crystalline CdS. Figure 3c shows a TEM image of CdS nanorods after the critical time under a TEM beam; the beginning of melting can also be seen. Figure 3d,e shows the TEM image of melted CdS nanorods and corresponding SAED pattern, respectively. After a critical time under the TEM beam, the initial morphology of CdS nanorods (Figure 2a) began to melt and, interestingly, the nanorods are transformed to smaller nanowires as shown in Figure 3c,d. The melting of nanorods and microstructural transformation to very small nanowires took place without any crystal phase transition. Also, some remaining islands of the melted nanorods can be seen in Figure 3d. This was confirmed by recording the diffraction patterns at various stages of the melting process of the nanorods. The diffraction pattern of the melted portion corresponds to cubic phase CdS with a lattice constant of a = 5.82 Å, which is similar to the diffraction pattern prior to the melting of the nanorods. The SAED pattern shown in Figure 3b,e corresponds to zinc blend CdS with high crystallinity. Also, the diffraction patterns shown in Figure 3b,c illustrate that the crystal structure remains intact before and after the melting of the nanorods. This phenomenon is very unique in CdS nanorods and could be potentially applicable for smart materials. Researchers have reported production of nanostructures using an electron beam [22]. Moreover, some studies have found an electron beam and its irradiation effect on optical and electrical properties of CdS thin films [23]. However, this is the first report of its kind that identifies the effect of TEM beam on CdS nanorods, where the morphology of nanorods was converted into nanowires with TEM beam energy after being exposed for a critical time.


Morphological variations in cadmium sulfide nanocrystals without phase transformation.

Dhage SR, Colorado HA, Hahn T - Nanoscale Res Lett (2011)

(a) and (b) TEM image corresponding diffraction pattern of single CdS nanorod; (c) TEM image at beginning of the melting of CdS nanorods; (d) TEM image of almost completely melted nanorods and corresponding diffraction pattern.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211837&req=5

Figure 3: (a) and (b) TEM image corresponding diffraction pattern of single CdS nanorod; (c) TEM image at beginning of the melting of CdS nanorods; (d) TEM image of almost completely melted nanorods and corresponding diffraction pattern.
Mentions: While analyzing the nanorods, the TEM beam current was 80 μA at accelerating voltage of 100 kV. Figure 3a,b shows a TEM image of a single nanorod and a corresponding diffraction pattern, respectively. The SAED pattern can be indexed for the zone axis of (111) single-crystalline CdS. Figure 3c shows a TEM image of CdS nanorods after the critical time under a TEM beam; the beginning of melting can also be seen. Figure 3d,e shows the TEM image of melted CdS nanorods and corresponding SAED pattern, respectively. After a critical time under the TEM beam, the initial morphology of CdS nanorods (Figure 2a) began to melt and, interestingly, the nanorods are transformed to smaller nanowires as shown in Figure 3c,d. The melting of nanorods and microstructural transformation to very small nanowires took place without any crystal phase transition. Also, some remaining islands of the melted nanorods can be seen in Figure 3d. This was confirmed by recording the diffraction patterns at various stages of the melting process of the nanorods. The diffraction pattern of the melted portion corresponds to cubic phase CdS with a lattice constant of a = 5.82 Å, which is similar to the diffraction pattern prior to the melting of the nanorods. The SAED pattern shown in Figure 3b,e corresponds to zinc blend CdS with high crystallinity. Also, the diffraction patterns shown in Figure 3b,c illustrate that the crystal structure remains intact before and after the melting of the nanorods. This phenomenon is very unique in CdS nanorods and could be potentially applicable for smart materials. Researchers have reported production of nanostructures using an electron beam [22]. Moreover, some studies have found an electron beam and its irradiation effect on optical and electrical properties of CdS thin films [23]. However, this is the first report of its kind that identifies the effect of TEM beam on CdS nanorods, where the morphology of nanorods was converted into nanowires with TEM beam energy after being exposed for a critical time.

Bottom Line: Environmentally stable and highly crystalline CdS nanorods have been obtained via a chemical bath method.The prepared CdS nanorods have been characterized by X-ray powder diffraction, TEM, UV-Vis spectroscopy, and photoluminescence spectroscopy.The importance of this phenomenon is vital for the potential application for CdS such as smart materials.

View Article: PubMed Central - HTML - PubMed

Affiliation: Mechanical and Aerospace Engineering Department, University of California, Los Angeles, CA 90095, USA. sanjay.dhage@gmail.com.

ABSTRACT
A very novel phenomenon of morphological variations of cadmium sulfide (CdS) nanorods under the transmission electron microscopy (TEM) beam was observed without structural phase transformation. Environmentally stable and highly crystalline CdS nanorods have been obtained via a chemical bath method. The energy of the TEM beam is believed to have a significant influence on CdS nanorods and may melt and transform them into smaller nanowires. Morphological variations without structural phase transformation are confirmed by recording selected area electron diffraction at various stages. The prepared CdS nanorods have been characterized by X-ray powder diffraction, TEM, UV-Vis spectroscopy, and photoluminescence spectroscopy. The importance of this phenomenon is vital for the potential application for CdS such as smart materials.

No MeSH data available.


Related in: MedlinePlus