Structural characterization of chemically synthesized CdSe nanoparticles (original) (raw)
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Surface and Interface Analysis, 2019
We report on the successful synthesis of CdSe nanoparticles (NPs) via a facile aqueous approach. Investigation on the effects of various cadmium sources in the precursor solution on the CdSe NPs is discussed. The structural and morphological properties characterized by the X-ray diffraction (XRD) and scanning electron microscope (SEM) displayed good features of the as-prepared CdSe NPs. The XRD pattern displayed a pure zinc blende crystal structure for all samples, with the most crystalline sample observed for CdSe NPs prepared using anhydrous cadmium chloride. The estimated crystallite sizes were below 6 nm for all the CdSe NPs samples. Mixed shapes of spherical and nanorods of varying sizes were observed from the SEM images for the as-prepared NPs prepared using different cadmium sources. The optical studies conducted by photo-spectroscopy pointed out the CdSe NPs prepared using anhydrous cadmium chloride gave the best optical properties. The emission wavelengths were in the range 565 to 574 nm while the optical band gaps were in the range 2.94 to 3.23 eV for all the as-prepared CdSe NPs samples. All the samples, however, displayed quantum confinement effects giving room for further fabrication and engineering to suit specific applications in the biological field. The obtained results demonstrated that aqueous phase synthetic route employed in this study could be successfully adopted for production of high-quality CdSe NPs because of its facile and inexpensive nature.
Raman spectroscopy study of the wurtzite-zinc blende phase transition of bare CdSe nanoparticles
Materials Science and Engineering: B, 2020
Structural and electronic properties characterization results show that the crystallographic structure of CdSe films, deposited by chemical bath synthesis, is controlled by the bath growth temperature. The synthesis parameters employed produced a set of nanostructured CdSe films on glass substrates with controlled crystal structure. The effect of bath temperature (T b) on CdSe films was studied in the 0 ≤ T b ≤ 80°C range. The average crystal diameter (AD) of the films lies within the 7 ≤ AD ≤ 12 nm interval, where AD depends on the selected T b. X-ray diffractograms (XRD) shown that at low T b values the formation of the hexagonal wurtzite (WZ) is promoted while at the other extreme the cubic zinc-blende (ZB) crystalline structure dominates. It is observed that the WZ → ZB transition occurs at the critical temperature T bc~4 0°C. The AD in each films for CdSe-NP's was obtained from XRD analysis employing the Scherrer-Debye formula. The values of the lattice interplanar spacing (IS), determined from XRD analysis, as function of T b increases continuously except at temperatures around T bc where a local minimum is observed. The presence of stress acting on CdSe NP's is identified by correlating the IS values with the crystalline structure: compression occurs for 0 ≤ T b ≤ 40°C, and tension for 50 ≤ T b ≤ 80°C. The band gap energy, obtained from optical absorption spectra, decreases monotonically but a local minimum is observed at T bc = 40°C. Results from Raman spectroscopy show that the CdSe Raman LO-mode hardens for T bc as consequence of the WZ ↔ ZB structural transition.
Applied Physics A, 2019
Cadmium sulfide (CdS) nanoparticles were prepared by hydrothermal method at 150 °C under different reaction times. It was found that hydrothermal method is an effective, quick, and eco-friendly method to synthesis CdS nanoparticles of hexagonal structure at lower temperature. X-ray peak profile analysis by Williamson-Hall analysis and size-strain plot was employed to estimate the crystallite size and lattice strain of the synthesized CdS nanoparticles and to investigate their effects on the peak broadening. The values of strain, stress and energy density were determined for all XRD peaks of wurtzite hexagonal phase of CdS, by applying various forms of Williamson-Hall procedure, such as UDM (uniform deformation model), USDM (uniform stress deformation model) and UDEDM (uniform deformation energy density model). The obtained results indicate that the crystallite size of CdS nanoparticles estimated from Scherrer equation, Williamson-Hall plots and size-strain plot, are nearly similar and in the range of 14-37 nm. CdS nanoparticles were also investigated using high-resolution transmission electron microscopy (HR-TEM), Fourier transform infra-red spectroscopy (FT-IR), and UV-visible and fluorescence spectroscopy. A dependence of the band gap and the nanoparticle size on the reaction time was reported.
science direct , 2010
One dimensional semiconductor nanorods of CdSe were successfully synthesized by solvothermal method using hydrazine hydrate (HH) and ethylenediamine tetraacetic acid (EDTA) as complexing agents. The average diameter of nanorods was found to be around 30 nm and 40 nm from XRD analysis. Thus there is a strong blue-shift in the absorption spectra for both the samples HH and EDTA capped CdSe, indicating that particles must be smaller than the exciton Bohr radius. The emission peak (PL) observed at 560 and 562 nm is attributed to the recombination of charge carriers on the surface of the nanorods.
A facile route for preparation of CdS nanoparticles
2007
CdS nanoparticles have been synthesized by a chemical reaction route using ethylenediamine as a complexing agent. The nanoparticles were characterized using techniques such as X-ray powder diffraction (XRD), scanning electron microscope (SEM), UV-VIS absorption spectroscopy, and photoluminescence spectroscopy. The absorption edge for the bulk hexagonal CdS is at 512 nm (2.42 eV). Comparing with the bulk CdS, it is believed that the blue shift in the absorption peak was caused by the quantum confinement effect. Photoluminescence measurements indicate CdS nanoparticles show fluorescence band with a maximum close to 315 nm.
TURKISH JOURNAL OF CHEMISTRY, 2021
Cadmium dithiocarbamate and cadmium ethyl xanthate complexes were synthesized and characterized by microanalysis, Fourier transform infrared (FT-IR) spectroscopy and thermogravimetric analyses. The complexes were employed as molecular precursors for the fabrication of CdS nanoparticles in hexadecylamine (HDA) and oleylamine (OLA) at a temperature of 250 °C. Spherical and oval shaped particles with sizes ranging from 9.93 ± 1.89 to 16.74 ± 2.78 nm were obtained in OLA while spherical, oval and rod shaped particles with sizes ranging from 9.40 ± 1.65 to 29.90 ± 5.32 nm were obtained in HDA. Optical properties of the nanoparticles showed blue shifts as compared to the bulk CdS, with the OLA capped nanoparticles slightly more blue shifted than the corresponding HDA capped nanoparticles. Results of crystallinity patterns revealed hexagonal phase of CdS.
Synthesis and analysis of ZnO and CdSe nanoparticles
Pramana, 2005
Zinc oxide and cadmium selenide particles in the nanometer size regime have been synthesized using chemical routes. The particles were capped using thioglycerol in case of ZnO and 2-mercaptoethanol in case of CdSe to achieve the stability and avoid the coalescence. Zinc oxide nanoparticles were doped with europium to study their optical properties. A variety of techniques like UV-Vis absorption spectroscopy, X-ray diffraction (XRD), photoluminescence (PL), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and transmission electron microscopy (TEM) were used to carry out structural and spectroscopic characterizations of the nanoparticles.
Synthesis and Characterization of CdS, ZnS and CdZnS Nanoparticles Embedded in Polystyrene
Journal of Modern Physics, 2014
The nano dispersions (colloids) of Cadmium Sulfide, Zinc Sulfide and Cadmium Zinc Sulfide were prepared by modified metathesis reaction between CdCl 2 , ZnCl 2 and Na 2 S. The prepared sulfides were embedded in polystyrene to form nano-composites. The size, morphology and composition of the nanoparticles on the surface of the composites were examined by using UV/VIS Spectroscopy, Scanning Electron Microscopy (SEM), High Resolution Transmission Electron Microscopy (HRTEM), Energy Dispersive Spectroscopy (EDS) and Particle Induced X-ray Emission (PIXE). The UV-spectrum shows a shift in the band gap towards high energy while the High Resolution Transmission Electron Microscope (HRTEM) analysis shows well resolved nanoparticles with particle sizes between 2-10 nm. The SEM shows that the nanoparticles are in form of nano clusters. The blue shift of the absorption band makes it possible to evaluate the size of the nanocrystallites, which is in agreement with that obtained from HRTEM. The composition as revealed by the EDS shows that the ratios of Cd:S, Zn:S and Cd:Zn:S are approximately 23:20, 58:42 and 32:35:33, respectively. The PIXE spectra confirmed the presence of expected elements and also reveal the presence of impurities.