Raman spectra of CdS nanocrystals in Nafion: longitudinal optical and confined acoustic phonon modes

Nandakumar, P.; Vijayan, C.; Rajalakshmi, M.; Arora, Akhi̇lesh; Murti, Y. V. G. S.

doi:10.1016/s1386-9477(01)00157-6

Cited by 79 publications

(42 citation statements)

References 23 publications

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“…In general, a narrow Raman peak points to a nanostructure with perfect crystal structure while a broad Raman line indicates polycrystalline nature of the sample. 46 Judging from the Raman spectra depicted in Fig. 5, we can suggest that the synthesized NPs are highly crystalline and relatively free of impurities, which is reflected by the small line width and rather symmetric line profiles.…”

Section: Raman Spectramentioning

confidence: 75%

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

et al. 2015

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In the present study, monodispersed CeO2 nanoparticles (NPs) of size 8.5 ± 1.0, 11.4 ± 1.0 and 15.4 ± 1.0 nm were synthesized using the sol-gel method. Size-dependent structural, optical and magnetic properties of as-prepared samples were investigated by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), high resolution transmission electron microscopy (HR-TEM), ultra-violet visible (UV-VIS) spectroscopy, Raman spectroscopy and vibrating sample magnetometer (VSM) measurements. The value of optical band gap is calculated for each particle size. The decrease in the value of optical band gap with increase of particle size may be attributed to the quantum confinement, which causes to produce localized states created by the oxygen vacancies due to the conversion of Ce4+ into Ce3+ at higher calcination temperature. The Raman spectra showed a peak at ∼461 cm-1 for the particle size 8.5 nm, which is attributed to the 1LO phonon mode. The shift in the Raman peak could be due to lattice strain developed due to variation in particle size. Weak ferromagnetism at room temperature is observed for each particle size. The values of saturation magnetization (Ms), coercivity (Hc) and retentivity (Mr) are increased with increase of particle size. The increase of Ms and Mr for larger particle size may be explained by increase of density of oxygen vacancies at higher calcination temperature. The latter causes high concentrations of Ce3+ ions activate more coupling between the individual magnetic moments of the Ce ions, leading to an increase of Ms value with the particle size. Moreover, the oxygen vacancies may also produce magnetic moment by polarizing spins of f electrons of cerium (Ce) ions located around oxygen vacancies, which causes ferromagnetism in pure CeO2 samples.

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Section: Raman Spectramentioning

confidence: 75%

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

et al. 2015

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“…Photoluminescence spectra of ZnO nanorod and CdS-ZnO composite nanorod mode of hexagonal ZnO is observed at 439 cm -1 [13], whereas after CdS deposition, one can observe a couple of peaks at 301 cm -1 and 438 cm -1 . The peak at 301 cm -1 corresponds to 1LO from hexagonal CdS [14]. The peak exhibits an inhomogeneous broadening towards the lower wave number region which evidences the presence of ultra small CdS nanoparticles.…”

Section: Resultsmentioning

confidence: 94%

Enhanced Photocurrent from CdS Sensitized ZnO Nanorods

Nayak

Son²,

Kim

et al. 2012

Journal of Electrical Engineering and Technology

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-Structure and optical properties of cadmium sulphide-zinc oxide composite nanorods have been evaluated by suitable characterization techniques. The X-ray diffraction spectrum contains a series of peaks corresponding to reflections from various sets of lattice planes of hexagonal ZnO as well as CdS. The above observation is supported by the Micro-Raman spectroscopy result. The optical reflectance spectra of CdS-ZnO is compared with that of ZnO where we observe an enhanced absorption and hence diminished reflection from CdS-ZnO compared to that from only ZnO. A very small intensity of the visible photoluminescence peak observed at 550 nm proves that the ZnO nanorods have very low concentrations of point defects such as oxygen vacancies and zinc interstitials. The photocurrent in the visible region has been significantly enhanced due to deposition of CdS on the surface of the ZnO nanorods. CdS acts as a visible sensitizer because of its lower band gap compared to ZnO.

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“…In several semi-conductor materials, size-induced optical mode softening (red-shift) and acoustical mode hardening (blue-shift) effects are well known occurrences. Tensile and compressive strains affect the Raman spectra causing a red shift and a blue shift, respectively [47]. …”

Section: Raman Spectroscopymentioning

confidence: 99%

Laser-assisted synthesis, and structural and thermal properties of ZnS nanoparticles stabilised in polyvinylpyrrolidone

Onwudiwe

Krüger

Jordaan

et al. 2014

Applied Surface Science

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Research Highlights-Zinc sulphide (ZnS) nanoparticles were synthesised by laser irradiation -The structural and morphological properties of the prepared samples were analysed -Larger particles were obtained by using Na 2 S instead of TAA as the sulphur source.-Phonon softening and line broadening of the peaks were observed -Size reduction occurred in the samples obtained from both sources Graphical Abstract AbstractZinc sulphide (ZnS) nanoparticles have been synthesised by a green approach involving laser irradiation of an aqueous solution of zinc acetate (Znac 2 ) and sodium sulphide (Na 2 S·9H 2 O) or thioacetamide (TAA) in polyvinylpyrrolidone (PVP). The structural and morphological properties of the prepared samples were analysed using a transmission electron microscope, TEM, a high resolution transmission electron microscope, HRTEM, X-ray diffraction, and Raman spectroscopy.The thermal properties were studied using a simultaneous thermal analyser (SDTA). Better dispersed and larger particles were obtained by using sodium sulphide (Na 2 S) instead of TAA as the sulphur source. X-ray diffraction (XRD) analyses and Raman measurement show that the particles have a cubic structure, which is usually a low temperature phase of ZnS. There were phonon softening and line broadening of the peaks which are attributed to the phonon confinement effect. The average crystallite size of the ZnS nanoparticles estimated from the XRD showed a reduction in size from 13.62 to 10.42 nm for samples obtained from Na 2 S, and 9.13 to The absorption spectra showed that the nanoparticles exhibit quantum confinement effects.

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Raman spectra of CdS nanocrystals in Nafion: longitudinal optical and confined acoustic phonon modes

Cited by 79 publications

References 23 publications

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

Controlled synthesis and magnetic properties of monodispersed ceria nanoparticles

Enhanced Photocurrent from CdS Sensitized ZnO Nanorods

Laser-assisted synthesis, and structural and thermal properties of ZnS nanoparticles stabilised in polyvinylpyrrolidone

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