Size Of Cadmium Sulfide Nanoparticles Research Articles

Synthesis and Characterization of γ-Irradiated Cadmium Sulfide/Polyvinyl Alcohol Nanocomposites Films

CdS (Cadmium Sulfide)/PVA (Polyvinyl Alcohol) nanocomposite films were prepared using a solution casting method. Transmission electron microscopy (TEM) showed that CdS nanoparticles (NPs) have particle size < 20 nm. X-ray diffraction (XRD) were used to check the crystal structure, grain size of CdS NPs in Polyvinyl alcohol (PVA) and the change in grain size of CdS with γ-irradiation doses. Fourier transform infrared (FTIR) spectroscopy has confirmed the dispersion of CdS NPs in PVA for fresh and γ-irradiated films, where a substantial change in band position (OH stretching) was noted due to the interaction between CdS NPs and the host PVA polymer matrix. Conductivities (DC/AC) and dielectric properties were used to characterize the final nanocomposite films before and after γ-irradiation with distinct doses. Upon increasing the amount of CdS NPs an increase in the dielectric constant (e1), dielectric loss (e2) and AC conductivity of PVA films host was observed. In addition, the DC and AC conduction of the PVA films as a polymeric host material was improved with the CdS NPs content and γ-irradiation doses.

X-ray peak profile analysis and optical properties of CdS nanoparticles synthesized via the hydrothermal method

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.

The influence of water–organic solvent composition on the morphology and luminescent properties of CdS nanoparticles obtained by chemical precipitation

Cadmium sulfide (CdS) nanoparticles have been obtained by chemical precipitation onto the surface of single-crystalline silicon from an aqueous solution of ammonia, cadmium chloride (CdCl2), and thiourea, as well as from water–DMSO and water–DMF mixtures with the same concentrations of the reagents. According to data of atomic force microscopy, the samples obtained from the aqueous solution consist of individual nanoparticles and agglomerates thereof with sizes of no larger than 1 µm. Materials obtained from the water–organic mixtures are distinguished by the aggregation of CdS nanoparticles into threadlike chains. The length of the formed curved chains and the size of CdS nanoparticles composing them depend on the nature and amount of an organic component of a mixture. Atomic force microscopy, transmission electron microscopy, and photoluminescence spectroscopy data have shown that the average size of CdS nanoparticles is 2–2.5 nm depending on solvent composition.

Synthesis and Characterization of Cadmium Sulfide Nanoparticles by Chemical Precipitation Method.

Cadmium sulfide (CdS) nanoparticles were synthesized by chemical precipitation method using cadmium chloride (CdCl2), sodium sulfide (Na2S) and water as a solvent by varying temperatures from 20-80 degrees C. The nanoparticles were characterized by X-ray diffraction (XRD), Raman spectroscopy, field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), High-resolution transmission electron microscopy (HR-TEM) and UV-Visible spectroscopy. XRD pattern revealed cubic crystal structure for all the synthesized CdS nanoparticles. Raman spectra showed first and second order longitudinal optical (LO) phonon vibrational modes of CdS. The size of CdS nanoparticles was found to be in the range of 15-80 nm by FE-SEM analysis, in all cases. The atomic percentage of cadmium and sulfur was confirmed to be 1:1 from EDS analysis. TEM micrograph depicts the spherical shape of the particles and the size is in the range of 15-85 nm while HR-TEM images of CdS nanoparticles exhibit well-resolved lattice fringes of the cubic structure of CdS. The optical properties of CdS were examined by UV-Visible spectroscopy which showed variation in absorption band from 460-480 nm. The band gap was calculated from the absorption edge and found to be in the range of 3.2-3.5 eV which is greater than the bulk CdS.

An approach to hybrid inorganic nanoparticles in reactive PS-b-PMSMA amphiphilic copolymers

A series of well-defined amphiphilic poly(styrene)-block-poly 3-(trimethoxysilyl) propyl methacrylate (PS-b-PMSMA) copolymers with controlled molecular weight and block length were prepared by the atom transfer free radical polymerization. The cadmium sulfide (CdS) nanoparticles were fabricated in the spherical micelles self-assembled from these prepared PS-b-PMSMA copolymers. Then, the CdS/PS-b-PMSMA films were obtained by spin coating the CdS/PS-b-PMSMA solution on silicon wafer. The experimental results showed the addition of Cu(II) could decrease the value of polydispersity index for the prepared copolymers. Nuclear magnetic resonance and Fourier transform infrared spectra showed the synthesis of PS-b-PMSMA copolymer. The average roughness and mean square roughness of the prepared CdS/PS-b-PMSMA films obtained from the atomic force microscopy analysis were 3.0–3.4 nm and 1.7–2.0 nm, respectively, indicating the excellent surface planarity. On the other hand, the ratio of block length between PS and PMSMA had a great influence on the micelle size. The larger ratio of PS to PMSMA block length resulted in the larger size of micelles and CdS nanoparticles that caused a red-shift of ultraviolet–visible and photoluminescence spectra. The red-shift of spectra was explained by the quantum confinement effect associated with the tiny size of the CdS nanoparticles.

Temperature Dependent Luminescence of Azobenzene Capped CdS Quantum Dots

Cadmium sulfide (CdS) quantum dots (QDs) are prepared at room temperature by "form-fill-seal" method, while the azobenzene is used as surfactant to control the particle size and to prevent agglomeration. The typical size of CdS nanoparticles is estimated as 2 nm by X-ray diffraction. The absorption spectra of CdS QDs are measured at room temperature and a new absorption peak associated with the surface excited state is found. The luminescence property of the CdS QDs is studied at room temperature and low temperature. Two photoluminescence peaks exist in the temperature range of 8-300 K. One peak at 460 nm is attributed to CdS QDs, while the other one at 667 nm comes from the transition of surface excited state and its intensity decreases with temperature increasing.

Electroluminescent properties of CdS/CNT hybrid material

AbstractAligned multiwall carbon nanotube (CNT) arrays were used for deposition of cadmium sulfide (CdS) nanoparticles from an aqueous solution containing thiourea, CdCl2, and ammonia. Scanning electron microscopy (SEM) showed that used deposition technique does not destroy vertical orientation of CNTs to silicon substrate. The size of CdS nanoparticles formed on the side surface and ends of CNTs was estimated by transmission electron microscopy (TEM) to be about 30 nm. It was found that CdS nanoparticles became luminescent during field electron emission from CNTs. Different color of the luminescence image was related to different size of the nanoparticles.magnified imageScheme of appearance of electroluminescence from CdS/CNT hybrids and image of luminous cathode surface.

Spectroscopic determination of the size of cadmium sulfide nanoparticles formed under environmentally relevant conditions

A multi-technique approach was adopted using UV/visible spectroscopy, fluorescence spectroscopy, dynamic light scattering (DLS), and transmission electron microscopy (TEM) in the characterization of cadmium sulfide (CdS) nanoparticles. CdS nanoparticle sizes could be determined by the Brus equation, which relates the UV/vis spectroscopic properties of CdS nanoparticles to size based on the quantum confinement effect. The diameters calculated from the wavelength of absorbance in UV/vis spectra were within 10% of the mean nanoparticle diameter measured in TEM. UV/vis spectroscopy provided an aqueous phase measurement of the CdS core size of the nanoparticles (<2 nm to approximately 10 nm diameter) that is based on a physical property rather than light scattering. CdS nanoparticles readily formed upon addition of sulfide to a Cd(ii)-thiolate complex with the thiolate molecules acting as capping agents that passivate the nanoparticle surface, thereby preventing bulk mineral precipitation. Using UV/vis as a method of nanoparticle sizing, we were able to demonstrate how aqueous conditions dictate the resulting nanoparticle size. High pH, capping thiolate concentration and Cd : S ratio all resulted in smaller nanoparticles. Ionic strength did not influence nanoparticle size, but DLS data indicate the formation of aggregates above ionic strengths of 0.1 M.

Biological Synthesis of Size-Controlled Cadmium Sulfide Nanoparticles Using ImmobilizedRhodobacter sphaeroides

Size-controlled cadmium sulfide nanoparticles were successfully synthesized by immobilizedRhodobacter sphaeroidesin the study. The dynamic process that Cd2+was transported from solution into cell by livingR. sphaeroideswas characterized by transmission electron microscopy (TEM). Culture time, as an important physiological parameter forR. sphaeroidesgrowth, could significantly control the size of cadmium sulfide nanoparticles. TEM demonstrated that the average sizes of spherical cadmium sulfide nanoparticles were 2.3 ± 0.15, 6.8 ± 0.22, and 36.8 ± 0.25 nm at culture times of 36, 42, and 48 h, respectively. Also, the UV–vis and photoluminescence spectral analysis of cadmium sulfide nanoparticles were performed.

Relationship between size of cadmium sulfide nanoparticles and water pool diameter in reverse micelles

Preparation of CdS nanoparticles in water sodium bis(2-ethylhexyl) sulfosuccinate isooctane reverse micelles with various water contents is studied. A direct correlation between the water pool diameter in the reverse micelles and the mean size of CdS nanoparticles is found. DOI: 10.1134/S1070427207090212 Recently a great interest has been attracted to prep- aration and characterization of nanomaterials (1). Reverse micelles in hydrocarbon solvents proved to be appropriate systems for nucleation and growth of nanoparticles. Water droplets (pools) in surfactant- based micelles act not only as microreactors, but also as steric inhibitors of aggregation of atoms and mole- cules. Micellar synthesis was used to prepare various nanomaterials, among them CdS (see review (2)). Cadmium sulfide is a semiconductor used as a work- ing medium in lasers and also as a material for fab- rication of photoresistors, photodiodes, and solar bat- teries. The advantages of the synthesis of nanopar- ticles in reverse micelles are, first, in mild conditions of the process (no high temperature and pressure is required) and, second, in that the size and shape of nanoparticles can be controlled by the micelle struc- ture and dynamics. Presently, in this research field, the major focus is on preparation and characterization of nanoparticles, but not on properties of the dispersions. Particularly, it remains to be understood whether the properties of the micelles and microemulsions are different in the course of synthesis of nanoparticles.

γ-Irradiation preparation of CdS nano-particles and their formation mechanism in non-water system

Cadmium sulfide nano-particles with mean size of 2.3 nm have been successfully prepared by irradiating an ethanol solution of cadmium chloride and carbon disulfide with 60Co γ-ray. The product is characterized by X-ray powder diffraction, transmission electron microscopy and X-ray photo-electron spectrum, respectively. The influence of the irradiation dose on the size of cadmium sulfide nano-particles is investigated by UV–VIS absorption spectrum. A possible mechanism for the formation of cadmium sulfide nano-particles in ethanol system is proposed according to the result of experiments.