Y. C. Goswami

Synthesis of SnO2 nanostructures by ultrasonic-assisted sol-gel method

Fluorine doped SnO2 nanostructures were grown using ultrasonic assisted sol–gel method. The gel was obtained by dissolving stannous chloride in methanol with ammonium fluoride as dopant followed by irradiation with ultrasonic vibrations. Obtained samples were characterized by structural, morphological and optical studies. All the peaks in the X-ray diffractograms are identified and indexed as tetragonal cassiterite structure. Negative slope of Williamson–Hall plots indicates compressive strain. Particle size of SnO2 nanostructures is decreases with increases in concentration of fluorine doping. Atomic force microscopy, scanning electron microscopy and transmission electron microscopy studies confirm the formation of ring like porous structures and then hollow tube like growth with increase in the fluorine concentration. Peaks in Raman spectra also indicate strong confinement in SnO2 particles. Distinct peaks in the PL spectra make the structure suitable for photovoltaic applications.

Optically Enhanced SnO2/CdS Nanocomposites by Chemical Method and Their Characterization

SnO2/CdS heterostructures nanocomposites were synthesized using newly develop ultrasonic sol-gel method. Stannous chloride, cadmium chloride (CdCL2 · 2H2O) and thiourea were used as Sn, Cd and S precursors respectively and Ethylene glycol was used as a complexing agent. The samples were characterized by XRD, SEM, EDX, optical studies. All the XRD peaks are identified for SnO2 however a slight shift is observed with addition of CdS. EDX confirms the presence of Sn, Cd and S in the samples. AFM and SEM studies also confirm the nanofibers structures with roughness 2.9136 nm and conversion of hollow tubes into nanofibers. The UV–Vis spectrum of the nanostructures displays a new absorption band range lies in the range between 450–530 nm compared with the bare SnO2 hollow tubes. The strong emission peak is observed at 375 nm in UV region for all the samples and intensity of emission become weaker due to incorporation of CdS nanoparticles. Addition of CdS introduces effective charge separation in the heterostructures which controlled the intensity of photo luminescence makes them suitable for optoelectronic applications.

Synthesis of Cu doped ZnS nanostructures on flexible substrate using low cost chemical method

Flexible electronics is one of the emerging area of this era. In this paper we have reported synthesis of Cu doped Zinc sulphide nanostructures on filter paper flexible substrates. Zinc chloride and Thio urea were used as a precursor for Zinc and Sulphur. The structures were characterized by XRD, FE-SEM and UV visible spectrometer. All the peaks identified for cubic structure of ZnS. Appearance of small Cu peaks indicates incorporation of Cu into ZnS lattice. Zns nanostructures assembled as nanobelts and nanofibers as shown in FE-SEM micrographs. Compound Structures provide the reasonable electrical conductivity on filter paper. Absorption in UV region makes them suitable for flexible electronic devices.

Growth of Green and Blue Luminescent Cu Doped CdS Nanorods and Their Optical Structural Characterization

Highly luminescent Copper doped CdS nanorods were prepared by modified sol-gel method. The sol was prepared by continuous stirring of mixture of ethylene glycol, ethanol and acetic acid with Cadmium chloride (CdCl2) and thiourea as the precursors of Cd and S respectively at 50 °C temperature for 3 h. For Cu doping cuprous chloride was added slowly. Fine green and blue colored particles were obtained. The samples were analyzed by XRD, SEM, optical transmission and photoluminescence studies. Broad peak of (101) is observed in X-ray diffractograms for undoped CdS. Intensity of this peak increases with increase in copper (Cu) doping. In SEM, large number of islands is observed in undoped CdS. On doping with copper these islands grow as more and more particles bind together. Undoped structures are generally spherical with uniform size and start to reassemble in ordered rodlike structure on increase in doping.

Growth of Blue Luminescent Cu Doped ZnO Nanowires by Modified Sol-Gel

Copper doped ultra small highly luminescent ZnO nanowires were obtained by modified sol gel route. The zinc acetate mixed with ethanol was used as precursor for the synthesis. Copper doping was done by adding various concentrations of copper chloride. Gel was obtained by magnetically stirring the mixture at 60 °C for 2–3 h and then keeping it for another 24 h for aging. The particles obtained were characterized by XRD, AFM, Optical transmission and photoluminescence studies. X ray diffractogram peak is identified for ZnO. AFM micrograph shows particle alignment in linear direction and formation of nanowires on increasing Cu concentration. The optical band gap of copper doped ZnO shift from 3.2 to 4.76 eV. This strong shift confirms the ultra small size of particles. In PL studies, Undoped ZnO nanostructures exhibit a near-band-edge UV emission at 360 nm and a broad defect related blue emission at 440 nm. Addition of Copper improves the photoluminescence peak in UV region with an additional peak observed in middle UV region at 230 nm. Yellow green or blue makes the nanowires suitable for light emitting devices and biological sensing devices.

Microwave Assisted Synthesis of Highly Luminescent ZnS Nanostructures Using Zinc Dithiocarbazic Complex Chemical Route

Bis(parahydroxyacetophenonebenzyldithiocarbazate) zinc(II) and bis(acetophenonebenzyldithiocarbazate) zinc(II) complexes have been synthesized. Zinc sulphide nanostructures were obtained from both complexes at different deposition temperatures using microwave assisted chemical route. The surface morphology of as-prepared ZnS nanoparticles were obtained using X-ray diffraction (XRD), transmission electron microscopy (TEM) and high transmission electron microscopy (HRTEM). Particles with spherical shape are shown in the TEM images of these samples. The optical properties of the particles studied by UV–Vis and photoluminescence (PL) spectroscopy showed evidence of quantum confinement.