Synthesis and characterization of CdS nanoparticles

In the present work a chemical reduction method is followed to grow CdS nanoparticles at room temperature with varying the amount of reducing agent sodiumborohydride. The dispersed samples in ethanol are characterized using electron diffraction techniques. Simultaneously optical absorption, photoluminescence and longtime photorelaxation of these samples are studied at room temperature. An increase in band gap is observed in each case as compared to bulk CdS. Also particle size decreases with increased amount of reducing agent. Simultaneously long time relaxation increases with decrease of stoichiometric ratio of reducing agent. An attempt is made to correlate the structural, optical, electrical and opto-electrical properties.     

CdS半导体纳米粒子合成与表征

以羟基化SBS为模板,乙酸镉、硫化钠为反应前驱物,利用盐诱导方式在四氢呋喃-甲醇-水体系中制备得到CdS纳米粒子。通过紫外-可见吸收光谱、荧光光谱及透射电子显微镜对CdS纳米粒子的光学性质及形貌进行了表征。结果表明,利用嵌段聚合物的两亲性质,可以得到稳定的具有明显量子尺寸效应的CdS半导体纳米粒子,透射电子显微镜结果表明所得到的CdS半导体纳米粒子具有冠状复合胶束结构。     

Synthesis and characterization of CdS doped TiO2 nanocrystalline powder: A spectroscopic study

This report aimed to study the effect of CdS doping in TiO₂ on the phase transformation of TiO₂ from anatase to rutile using X-ray diffraction (XRD) and Raman spectroscopy. CdS-doped TiO₂ nanocomposites have been prepared and characterized using Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). We have observed that contrary to bare TiO₂, phase transformation of TiO₂ from anatase to rutile is hindered when doped with CdS at high temperature. Raman spectroscopy is found to be more sensitive for detection of the surface of TiO₂ as compared to XRD.     

Synthesis and characterization of cadmium doped lead-borate glasses

Cadmium doped lead-borate glasses were prepared from the melts in appropriate proportions of PbO₂, H₃BO₃ and (15–40 mol%) CdO mixture in the temperature range 700–950°C. The infrared spectra of the glasses in the range 400–4000 cm^-1 show their structures. No boroxol ring formation was observed in the structure of these glasses. Furthermore, doped cadmium atoms were not seen in tetrahedral coordination. But the conversion of three-fold to four-fold coordination of boron atoms in the structure of glasses was observed.     

基于大分子配体修饰的Cd2+、Mn2+掺杂功能化ZnS纳米晶的制备与表征

以醋酸锌、氯化镉、醋酸锰和硫化钠为原料,采用末端带双键的聚甲基丙烯酸(PMAA)大分子单体为配体,在水溶液中成功制备出分散均匀并具有良好荧光性的Cd2+和Mn2+掺杂复合的ZnS纳米晶.利用电导率分析、TGA、Uv-vis、荧光光谱(PL)等表征手段考察了复合纳米晶结构和光学性能的关系.结果表明,PMAA中的大量羧基是以配位键的形式和纳米晶表面金属原子相结合.通过改变掺入的Cd2+的含量,能够获得从紫外光到可见光范围的ZnS:Cd2+复合纳米晶材料.     

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.     

Synthesis and characterization of poly(N-vinylpyrrolidine)-silica hybrid shell coated cadmium selenide / cadmium sulphide and cadmium selenide / zinc sulfide nanoparticles

Poly(N-vinylpyrrolidine)-silica hybrid shell coated cadmium selenide / cadmium sulphide and cadmium selenide / zinc sulfide nanoparticles were synthesized by combining the organometallic and single “step” modified Stober method. The synthesized nanoparticles were characterized by atomic force microscopy (AFM), Fourier transform infrared (FTIR) spectroscopy, and a spectrofluorometer. Concluding, this report has provided important insights into the design of new water-soluble polymer silica hybrid shell coated quantum dots nanoparticles for biomedical, analytical and catalytic applications.     

Synthesis and characterization of nickel ferrite magnetic nanoparticles

Nickel ferrite (NiFe₂O₄) nanoparticles are prepared by a polyvinyl alcohol (PVA) assisted sol-gel auto-combustion method. The structure, composition, morphology and magnetic properties of the gel precursor are characterized by powder XRD, FT-IR, TGA, HR-SEM, TEM, HR-TEM and VSM. XRD confirms the formation of single-phase nickel ferrite with space group of Fd3m and inverse spinel structure. The vibration properties of nanoparticles are analysed by FT-IR spectrum. The thermal decomposition of the gel precursors is investigated by TGA. HR-SEM and TEM images show that the particles have spherical shape with particle size in the range of ∼30 nm and consistent with XRD result. The magnetic properties of these nanoparticles are studied for confirming the ferromagnetic behaviour at room temperature.     

Synthesis and characterization of bismuth doped barium sulphide nanoparticles

We have synthesized BaS:Bi nanocrystalline powder of average grain size 35 nm by solid-state diffusion method using sodium thiosulphate as a flux. During this work we have optimized the nature and amount of flux, amount of the dopant and temperature of firing for maximum yield of photoluminescence. The samples were characterized by X-ray powder diffraction (XRD) method, transmission electron microscopy (TEM), photoluminescence (PL) and UV-visible techniques. On excitation by 425 nm, these nanophosphors give one emission peak at 575 nm which corresponds to green color. In the excitation spectra of these particles there are two peaks at 350 nm and 425 nm. The effect of dopant concentration on the photoluminescence of BaS:Bi nanocrystallites has been studied which is in agreement with the principle of concentration quenching. The energy band gap of bismuth doped BaS nanopowder has been calculated to be 4.25 eV and is blue shifted in comparison to their bulk counterparts. The blue shift may be due to the quantum confinement in the particles.     

聚合物保护纳米镍粉的制备与表征

采用改进的多元醇液相还原工艺,用 1,2 丙二醇作还原剂,在聚乙烯吡咯烷酮(PVP)稳定剂保护下,通过调整反应条件,在均相成核条件下,合成了粒径 25nm,具有面心立方晶体结构的纳米镍粉,运用XRD、TEM、SAED、FTIR 等微观分析手段,研究了NaOH浓度、PVP加入量等因素对制备纳米镍粉的影响。研究发现NaOH可以提高成核速率,调节颗粒生长溶质浓度,是形成粒径均匀纳米颗粒的重要条件。适量的聚合物保护剂,可以阻止成核颗粒生长,减小粒径,防止颗粒团聚,FTIR分析显示PVP分子与纳米颗粒之间存在化学作用。     

Structural and magnetic properties of Ni doped CeO2 nanoparticles

We report room temperature ferromagnetism in Ni doped CeO2 nanoparticles using X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM), and dc magnetization measurements. Nanoparticles of Ce(1-x)Ni(x)O2 (0.0 < or = x < or = 0.10) were prepared by using a co-precipitation method. XRD measurements indicate that all samples exhibit single phase nature with cubic structure and ruled out the presence of any secondary phase. Lattice parameters, strain and particle size calculated from XRD data have been found to decrease with increase in Ni doping. Inter-planner distance measured from HR-TEM images for different Ni doped samples indicate that Ni ions are substituting Ce ions in CeO2 matrix. Magnetization measurements performed at room temperature display weak ferromagnetic behavior of Ce(1-x)Ni(x)O2 (0.0 < or = x < or = 0.10) nanoparticles. Magnetic moment calculated from magnetic hysteresis loop was found to increases with Ni doping up to 7% and then start decreasing with further doping.     

Cadmium sulfide and cadmium selenide/cadmium sulfide nanoparticles stabilized in water with poly(cysteine acrylamide)

Cysteine acrylamide (N-acryloyl L-cysteine) stabilizes CdS nanoparticles as the particles form in aqueous dispersions. Cysteine acrylamide also exchanges for citrate on the surfaces of CdSe and core/shell CdSe/CdS nanoparticles to provide greater stability. Heating of the nanoparticle dispersions polymerizes the cysteine acrylamide on the surface to form a more efficient polydentate stabilizer. The polymer-coated nanoparticle dispersions are colloidally stable even after removal of low molecular weight solutes by dialysis. Emission quantum yields of the polymer-coated CdSe and CdSe/CdS samples were 0.9% and 2.6%, respectively, after aging of the samples in light. CdSe/CdS coated with poly(cysteine acrylamide) is colloidally stable for at least two years in the dark at 5 degrees C.     

Synthesis and characterization of Fe doped CeO2 nanoparticles for pigmented ultraviolet filter applications

Iron doped CeO2 nanoparticles with doping concentrations between 0 and 30 mol% were synthesized by the co-precipitation method for potential application as a pigmented ultraviolet filtration material. Each sample was calcined in air and in argon. The iron solubility limit in the CeO2 lattice was found to be between 10 and 20 mol%. Raman spectroscopy results revealed that both iron doping and argon calcination increase the concentration of oxygen vacancies in the CeO2 lattice. Iron doping causes a blue-shift of the absorbance spectrum, which can be linked to the decreased crystallite size, as obtained by XRD peak broadening using the Scherrer formula. The undoped samples showed weak ferromagnetic behaviour whereas the doped samples were all paramagnetic.     

太阳光下Cr~(3+)掺杂TiO_2复合微粒光催化性能研究

利用酸催化的溶胶一凝胶法成功地合成了一系列不同CP3+掺杂量(x=0.01%～10%)的TiO2复合光催化剂(Cd3+/TiO2).在太阳光条件下,以亚甲基蓝溶液的光催化降解对复合材料的光催化性能进行了表征,并考察了催化剂投加量、Cr3+掺杂量和溶液pH值等因素对光催化降解反应的影响.结果表明,亚甲基蓝溶液在复合微粒上的光催化降解反应遵循Langmuir-Hinshelwood动力学模型,在催化剂投加量为lg/L、Cr3+掺入量为0.3%和pH=7时,Cr3+/TiO2复合微粒光催化活性达最佳,测得表观反应速率常数 K为7.27×10-3 rag(L·min)-1,t1/2为95min,反应4h后亚甲基蓝的降解率可达79%,与纯的TiO2相比较,反应速率提高了2倍,降解率提高了20%.中性或碱性条件下有利于亚甲基蓝溶液的光催化降解.     

Synthesis and characterization of undoped and TM (Co,Mn) doped ZnO nanoparticles

Antibacterial activity of Transition metals (Mn, Co) doped ZnO nanopowders prepared by a DC thermal plasma method against Escherichia coli and Staphylococcus aureus are investigated. The phase and morphology studies have been carried out by X-ray diffraction, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) respectively. All the samples of the present investigation are found to have hexagonal wurtzite structure and crystallite sizes are found to vary from 25 nm to 30 nm. Our bacteriological study showed the enhanced antibacterial activity of transition metals doped ZnO nanoparticles than undoped ZnO indicating the great potential of ZnO nanoparticles in relevant clinical and biomedical applications.     

Multicolor luminescence from transition metal ion (Mn2+ and Cu2+) doped ZnS nanoparticles

Mn and Cu doped ZnS nanoparticles in powder form were prepared by a simple solvothermal route. Particle size and crystal structure of the products were investigated through X-ray diffraction study revealing the formation of cubic ZnS nanoparticles of average diameter 2.5 nm. Particle size was also verified by the high resolution transmission electron microscopic images. Blue emission at approximately 445 nm was observed from the undoped sample, which was attributed to the presence of large surface defects. With increasing doping concentration the defect related emission gradually quenches and subsequently the impurity related emissions appeared. Mn doped samples exhibited orange emission at approximately 580 nm which may be attributed to the transition between (4)T1 and (6)A1 energy levels of the Mn2+ 3d states. Whereas, the Cu doped ZnS nanoparticles exhibited a red shifted strong blue emission at approximately 466 nm which is attributed to the transition of the electrons from the surface states to the 't2' levels of Cu impurities.     

Synthesis,characterization and optical properties of CdS nanoparticles confined in SBA-15

A novel and dexterous in situ method is introduced to load CdS nanocrystals into SBA-15, which uses the acid–base reaction of mercaptoacetic acid with 3-aminopropyltriethoxysilane, the modifier of internal surface of mesoporous materials to facilitate loading of sulfur precursor, followed by adsorption of Cd²⁺ and calcination at 300 °C in N₂ atmosphere for 2 h. XRD, N₂ adsorption–desorption isotherms, HRTEM, EDS, FT-IR, UV–vis absorption spectrum and PL spectrum were used to characterize the composite material. It was found that the CdS nanocrystals were confined in the channel of SBA-15 with an average size of 6 nm. The mesoporous silica-supported CdS composites showed a room temperature photoluminescence property.     

Electrogenerated chemiluminescence sensors using Ru(bpy)3(2+) doped in silica nanoparticles

A novel electrogenerated chemiluminescence (ECL) sensor based on Ru(bpy)3(2+)-doped silica (RuDS) nanoparticles conjugated with a biopolymer chitosan membrane was developed. These uniform RuDS nanoparticles (approximately 40 nm) were prepared by a water-in-oil microemulsion method and were characterized by electrochemical and transmission electron microscopy technology. The Ru(bpy)3(2+)-doped interior maintained its high ECL efficiency, while the exterior nanosilica prevented the luminophor from leaching out into the aqueous solution due to the electrostatic interaction. This is the first attempt to branch out the application of RuDS nanoparticles into the field of ECL, and since a large amount of Ru(bpy)3(2+) was immobilized three-dimensionally on the electrode, the Ru(bpy)3(2+) ECL signal could be enhanced greatly, which finally resulted in the increased sensitivity. This sensor shows a detection limit of 2.8 nM for tripropylamine, which is 3 orders of magnitude lower than that observed at a Nafion-based ECL sensor. Furthermore, the present ECL sensor displays outstanding long-term stability.