Characterization of CdS Nanoparticles Embedded in Polyvinyl Alcohol

다국어 초록 (Multilingual Abstract)

CdS nanoparticles embedded in a PVA (polyvinyl alcohol) matrix were prepared and characterized by using cadmium chloride (CdCl₂) and sodium sulfide (Na_2S). When CdCl₂of various molar concentrations was a mixed with a PVA aqueous solution, the -OH groups in PVA acted as coordinating sites for cadmium ion Cd^(2+) aggregations to form PVA-Cd^(2+) composites. The CdS nanoparticles embedded in PVA were successfully grown at these sites by dipping PVA-Cd^(2+) composites into a solution that contained 0.5 mM of S^(2-) ions from Na_2S. The optical band gaps of the nanoparticles were increased from 2.51eV to 2.74 eV by decreasing the molar concentration of CdCl₂from 5 mM to 0.5 mM, indicating that the size of the nanoparticles increased with increasing CdCl₂molar concentration. X-ray diffraction results showed that the CdS nanoparticles were in a cubic phase while their sizes,estimated to be 4.7 nm, 4.8 nm and 5.9 nm for CdCl₂concentrations of 0.7 mM, 1.0 mM and 3.0 mM, respectively, were almost identical to the values calculated by using Brus’s formula.
The PL emission spectra of the CdS nanoparticles formed by 0.7 mM of Cd^(2+)showed two peaks, one at 471 nm and the other at 606 nm,which were attributed to the band edge and to surface defects,respectively.

참고문헌 (Reference)

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