Preparation and structural characterisation of chemically deposited Pb1−xCdxS films

Alloy films of Pb_1−xCd_xS have been prepared on glass substrates by electroless deposition from a chemical bath. Structural characterisation of the alloy was carried out by x-ray powder diffraction technique using Debye-Scherrer camera. The study shows that Pb_1−xCd_xS exists in cubic phase and the lattice constants are found to be greater than individual CdS and PbS value. This expansion of lattice is possibly due to interstitials. The lattice constants have been found to vary linearly with atomic percent of cadmium sulphide. The SEM micrographs show that particle size increases with increase in atomic percent of cadmium sulphide in the alloy.     

Studies on CdIn2O4 derived from CdIn2S4 prepared by flux method

Stoichiometric and nonstoichiometric powders of cadmium indium oxide were derived from calcination of cadmium indium sulphide prepared by flux method. The materials were confirmed by XRD. Thick films of above prepared powders were prepared on glass substrates using screen printing technique. The thick films were characterized by SEM and EDAX. The electrical conductivity of CdIn₂O₄ thick films was calculated. The gas sensing performance of stoichiometric thick films of CdIn₂O₄ was tested for various gases. The films showed good response to LPG.     

Structural,optical and magnetic properties of Ba and Ni doped CdS thin films prepared by spray pyrolysis method

Pure, Barium and Nickel doped cadmium sulphide (CdS) thin films have been coated on glass substrates at 400?°C by spray pyrolysis technique. The prepared CdS and doped CdS thin films were analysed by various measurements such as X-ray diffraction (XRD), SEM, optical and Vibrating Sample Magnetometer (VSM). X-ray diffraction measurements show that the coated pure, Ba and Ni-doped CdS thin films belong to the cubic crystal structure with orientation preferentially along (111) direction. The average crystallite size of pure, Ba and Ni doped CdS thin films were determined as 31, 33 and 45 nm, respectively. The average dislocation density (δ) and stacking fault (SF) of pure, Ba and Ni doped CdS thin films were also determined. The surface morphology and elemental analysis of the thin films were determined by scanning electron microscopy and energy dispersive X-ray spectrum (SEM with EDAX). It is observed that the optical energy bandgap has been decreased from 2.43 to 2.1 eV due to the doping Ba. The luminescence spectrum shows a strong emission peak at 517 nm in the case of pure CdS thin film and a meager red shift has been observed due to the doping. VSM studies were employed to study the magnetic behaviour of Ba and Ni doped CdS thin films.     

Effect of Sulfur Precursor on Dimensions of One-dimensional CdS Nanocrystals

One-dimensional CdS nanocrystals have been prepared by solvothermal method using cadmium acetate as a cadmium precursor,elemental sulfur and Na2S,as a sulfur precursor,and ethylenediamine as a solvent at 150℃ for 5 h.The nanocrystals were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM) and UV-Vis absorption spectroscopy.XRD patterns indicate that both Na2S and elemental sulfur as the sulfur precursor result in CdS nanorods with wurtzite phase(h...     

Strong quantum confinement effect in nanocrystalline CdS

CdS quantum dots have been prepared by chemical method. The X-ray diffraction results indicated the formation of CdS nanoparticles with hexagonal phase and grain size 2.5 nm. The HRTEM analysis reveals the formation of CdS quantum dots with an average grain size of ~2.5 nm. The X-ray photoelectron spectroscopy spectra exhibit the 3d _5/2 and 3d _3/2 peaks corresponding to cadmium and the S2p _3/2 peak corresponding to sulphur. Optical studies by UV–vis spectroscopy show a blue shifted absorption at 471 nm because of the quantum confined excitonic absorption. The photoluminescence spectra of CdS exhibited a broad green emission band centred at around 494 nm.     

Photoluminescence study of PVP capped CdS nanoparticles embedded in PVA matrix

Photoluminescence properties of polyvinyl pyrrolidone (PVP) capped cadmium sulphide (CdS) nanoparticles embedded in polyvinyl alcohol matrix (PVA) are reported. The PVP-CdS nanoparticles are prepared by non-aqueous method wherein cadmium nitrate is used as the cadmium source and hydrogen sulphide as the sulphur source. The synthesized nanoparticles are dispersed in polyvinyl alcohol (PVA) matrix and cast as self-standing flexible (PVP-CdS)-PVA films. The nanocomposites are characterized by optical absorption spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies. XRD and TEM studies show the formation of cubic CdS particles with average size ∼3-5 nm. Thermal studies, carried out to observe the changes in PVA matrix due to the incorporation of PVP-CdS nanoparticles show strong interaction between the polymer matrix and nanoparticles. The photoluminescence emission spectra of the nanocomposites show two peaks, at 502 and 636 nm, which are attributed to the band edge and surface defects respectively, of CdS nanoparticles. Effective surface capping with optimum concentration of polyvinyl pyrrolidone leads to the quenching of surface defect-related emission.     

水热法合成铁掺杂的硫化镉及光催化性能

以硝酸镉、硝酸铁和硫脲为原料,水为溶剂,通过水热法一步合成铁掺杂的硫化镉。产物经SEM,XRD,EDS和XPS等技术进行表征,以亚甲基蓝的光催化降解为目标反应,评价其光催化活性。结果表明:水热温度对硫化镉的形貌影响较大,不同反应温度可分别得到球状、花状、簇状和棒状的硫化镉,其中花状硫化镉的光催化性能最高。XRD分析表明,160℃反应时,所得掺铁的硫化镉均为六方晶体结构。光催化实验表明,铁掺杂能进一步提高硫化镉的催化活性,当Fe和Cd的掺杂比为1∶10时,催化效果最佳。     

Preparation and characterization of EP/SiO<Subscript>2</Subscript> hybrid materials containing PEG flexible chain

EP/SiO₂ hybrid materials, which contained flexible chain, were prepared by epoxy resin (EP) and polyethylene glycol (PEG)-grafted polysilicic acid (PSA), which was obtained by endcapping polyethylene glycol-1000 with toluene 2,4-diisocyanate (TDI), followed by a reaction with polysilicic acid. The formation of hybrid materials was confirmed by a wide-angle X-ray diffraction (WAXD) and atomic force microscopy (AFM) analysis. Results showed that the EP/SiO₂ hybrid particles were nanosized and the average size was about 20–50 nm. The mechanical properties, dynamic mechanical properties, and thermal properties were evaluated and compared with the corresponding matrix. The improvement in impact properties in hybrid materials was explained in terms of the impact fracture surface analysis by scanning electron microscope (SEM).     

Application de la pulvérisation cathodique réactive à la fabrication de CdS photosensible

The photoconducting properties of CdS produced by reactive sputtering of Cd in a H₂S-argon mixture have been studied, the cadmium sulphide being deposited on glass plates provided with comb-shaped gold electrodes.     

微晶纤维素/CdS纳米复合材料的原位复合反应

以微晶纤维素(MCC)为模板,采用原位复合法制备MCC/CdS纳米复合材料。研究了超声波预处理以及镉离子、硫离子物质的量比对复合效果的影响,用扫描电镜(SEM),原子力显微镜(AFM),X射线衍射,荧光光谱(PL)以及激光共聚焦显微镜(CLSM)对复合材料的结构及性能进行表征。研究表明,超声波预处理后的纤维素对镉离子吸附能力更强,粒径为30 nm~100nm的CdS粒子均匀分布于纤维素表面,所得CdS为立方型晶体,复合材料体现出一定强度的光致发光性,较佳Cd2+∶S2-(物质的量比)为3∶1。     

2.15 The stoichiometry of surfaces in cadmium sulphide thin films

The sulphur to cadmium ratio in cadmium sulphide thin films has been compared to that of a clean single crystal using Auger spectroscopy. Thermally evaporated CdS films were found to be deficient in sulphur in their outer layers, but were stoichiometric after etching. Electron beam evaporated CdS films were found to be stoichiometric.It was found that baking these films at 190°C in argon or nitrogen at atmospheric pressure increased the sulphur to cadmium ratio, probably due to sulphur diffusing to the surface and being physisorbed there.From measurements of the temperature dependence of the copper sulphide layer in CdSCu₂S cells it was found that chalcocite, djurleite and diginite copper sulphide phases are present even in efficient cells. A model is proposed for the structure of the copper sulphide layer in which the copper deficient phases are the result of excess sulphur on the CdS surfaces and vary in thickness according to the degree of non-stoichiometry of the CdS surfaces.     

Synthesis and morphological control of europium doped cadmium sulphide nanocrystals

Europium doped cadmium sulphide (Cd(0.98)Eu(0.2)S) nanostructures were synthesised by chemical co-precipitation method using ethylene glycol (EG) and deionized water (Eu:CdS-1), and isopropyl alcohol (IPA) and deionized water (Eu:CdS-2) as mixed solvents. It has been found that the nanostructure of the europium doped CdS can be controlled by simply varying the mixed solvent system. Powder XRD pattern reveals the formation of hexagonal (wurtzite) and cubic (zinc blende) structure for Eu:CdS-1, and Eu:CdS-2, respectively. The crystallite size of the sample prepared using IPA and deionized water was measured to be 2.64 nm which is much smaller than that of the sample prepared using EG and deionized water as mixed solvent (3.65 nm). Morphology of the materials can also be changed from flower shaped crystals to paddy like structures by varying the mixed solvents. Band gap values of Eu3+ doped CdS nanocrystals synthesized from two different solvents were estimated using UV-reflectance spectra. The size and crystallinity of the samples were confirmed by HRTEM and SAED analysis. A significant change in the PL emission of the CdS nanocrystals was observed for the europium doped CdS which is mainly due to the presence of EU3+ ions which also play a significant role in the energy transfer process. It was also observed that the shift in the emission and efficiency depends on size and shape of the synthesised nanoparticles.     

Synthesis and characterization of CdS nanoparticles in polystyrene microfibers

We described the synthesis of hybrid fibers composed of cadmium sulfide (CdS) nanoparticles and polystyrene (PS) by an in-situ reaction method. Scanning electron microscopic (SEM) studies showed that the hybrid samples have a fiber-like morphology. Transmission electron microscopic (TEM) studies showed that CdS nanoparticles were embedded in PS fibers with a diameter from 10 to 20 nm. Fourier-transform infrared (FTIR), UV–vis spectrum and X-ray photoelectron spectra (XPS) were used to characterize the structure of the composite fibers. X-ray diffraction (XRD) results showed that a hexagonal CdS phase was obtained in the PS fibers.     

Evaporated Thin Films of CdS and CdTe: Optimization for Photovoltaic Applications

Thin films of cadmium sulphide and cadmium telluride have been prepared by thermal evaporation under various conditions of deposition. These films have been characterized optically. electrically and for structure determination. The results of these characterizations along with the initial results of all thin film CdS/CdTe solar cells are presented in this paper     

Effects of CdCl2 in CdTe on the properties of sintered CdS/CdTe solar cells

Sintered CdS films on glass substrates with low electrical resistivity and high optical transmittance have been prepared by a coating and sintering method. All-polycrystalline CdS/CdTe solar cells with different microstructures and properties of the CdTe layer were fabricated by coating a number of CdTe slurries, which consisted of cadmium and tellurium powders, an appropriate amount of propylene glycol and various amounts of CdCl₂, on the sintered CdS films and by sintering the glass-CdS-(Cd + Te) composites at various temperatures. The presence of more than 5 wt% of CdCl₂ in the (Cd + Te) layer enhances the sintering of the CdTe film and the junction formation by a liquid-phase sintering mechanism. A low sintering temperature results in poor densification of the CdTe layer and the CdS-CdTe interface, whereas a high sintering temperature results in a deeply buried homojunction. The optimum temperature for the sintering of the CdTe layer and for junction formation decreases with increasing amount of CdCl₂. All-polycrystalline CdS/CdTe solar cells with an efficiency of 10.2% under solar irradiation have been fabricated by a coating and sintering method using cadmium and tellurium powders for the CdTe layer.     

Optical studies on chemical bath deposited nanocrystalline CdS thin films

Nanocrystalline cadmium sulphide thin films were prepared by the chemical bath (CB) deposition using a mixed aqueous solution of cadmium chloride, thiourea, and ammonium chloride. The XRD patterns showed that the CdS films were of hexagonal phase with preferred (002) orientation. From ellipsometric measurements, the film thickness was found to be in order of 66 nm and the optical band gap was estimated to be 2.4 eV.     

Preparation of CdS microtrumpets from a solvent extraction system by a two-phase approach

CdS microtrumpets with the length being of about 4 μm and the bell wall being of 100 nm have been prepared using a cadmium di-(2-ethylhexyl) phosphoric acid chelate as the precursor by a two-phase thermal approach. The products were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and UV-vis spectroscopy. The effects of temperature, reaction time, and co-surfactant on the morphology were also examined. It was found that the co-surfactant triethanolamine plays a crucial role in the formation of the cubic phase trumpet-like CdS microstructures.     

Investigations of Al:CdS/PVA nanocomposites: A joint theoretical and experimental approach

In the present work we investigate the aluminium doped cadmium sulphide (Al:CdS) nanoparticles embedded in polyvinyl alcohol (PVA) matrix by chemical route and density functional theory (DFT) based simulations. Supertetrahedron (T_n) cluster models are considered for the simulation of CdS nanoparticles. Using DFT simulations on T_n clusters, we observe that band gap of ligated clusters is slightly more as compare to bare clusters. This indicates the ability of organic ligands (PVA) to open the band gap of inorganic CdS nanoclusters. Negative value of binding energy indicates the stability of the inorganic–organic hybrid system. Frontier molecular orbitals (FMOs) indicate the charge transfer between organic and inorganic moieties which provides stability and longevity to nanoparticles, a prime function of ligands in nanocomposites. Absorption spectra of pure and doped clusters are calculated using time dependent density functional theory (TDDFT). CdS/PVA and Al:CdS/PVA samples are synthesized at room temperature by chemical method. Their structure, size and band gap is characterized by XRD, TEM, FTIR and UV spectroscopy. Optical band gap values as observed experimentally are in agreement with simulated TDDFT results.     

Preparation of mixed (Cd,Bi)S composite thin films via surfactant facilitated electrodeposition process and their photoelectrochemical characterization

In the present investigation we explored possibilities of preparing mixed CdS–Bi₂S₃ composite thin films of nanodimensions using a single step surfactant facilitated electrochemical process from aqueous solutions containing different colloidal concentrations of CdS and Bi₂S₃ particles. As deposited composite thin films has been characterized on the basis of SEM, AFM and XRD studies for determination of their surface morphology, surface roughness and grain size. Photoelectrochemical characterization of these composite materials has been carried out on the basis of photopotential, current–voltage (I–V) characteristics under dark and illumination conditions and photoaction spectral studies. Attempt has also been made to estimate the resistance of these composite materials towards their electrochemical corrosion. As prepared mixed (Cd,Bi)S composite semiconductor film exhibits substantial improvement in their photoelectrochemical properties.     

Microwave-assisted template synthesis of an array of CdS nanotubes

An array of CdS nanotubes was successfully prepared in a porous anodic alumina (PAA) membrane under the assistance of microwave irradiation, employing CdCl₂ and thiourea as the starting materials. TEM and SEM observations clearly showed the tubular structure of the product. SAED and XRD patterns showed the as-prepared product was non-crystalline, but EDX analysis confirmed the formation of CdS in the PAA membrane.