Pure and Co-doped zinc oxide nanomaterials were prepared by a simple low temperature synthesis and were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution-transmission electron microscopy (HR-TEM), diffused reflectance spectroscopy (DRS) and electron paramagnetic resonance (EPR) techniques. The results showed the formation of nanobushes that consists of several nanowires for pure ZnO and the nanorods formed by self-aggregation for Co-doped ZnO. The presence of Co2+ ions replacing some of the Zn2+ in the ZnO lattice was confirmed by EPR and DRS studies. The mechanism for the formation of self-aggregated and self-aligned ZnO rods after the incorporation of cobalt in the lattice by the building block units is discussed in this study. Morphological studies were carried out using SEM and HR-TEM, which supports the validity of the proposed mechanism for the formation of ZnO nanobushes and Co-doped ZnO nanorods. The synthesized nanomaterials were found to have good optoelectronic properties. © 2010 Elsevier Ltd. All rights reserved.

John Kennedy L

Physics

School of Advanced Sciences

Chennai Campus

Freedsman J.J

Kumar R.T

Sekaran G

Vijaya J.J.

Vellore Institute of Technology (VIT) is a private university located in&nbsp;Tamil Nadu, India. Founded in 1984, as Vellore Engineering College, the institution offers 20 undergraduate, 34 postgraduate, four integrated and four research programs. It has campuses in Vellore, Amravati, Bhopal and Chennai.

VIT is one of the top ranked private universities in India according to NIRF, THE and QS Rankings.&nbsp;Govt. of India has recognized&nbsp;VIT, Vellore as an&nbsp;Institution of Eminence. This has allowed VIT to take independent quality initiatives and move up in world ranking.

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VIT University

Materials Research Bulletin

Zn1-xMnxAl2O4 (0 ≤ x ≤ 0.5) spinel nanostructures were synthesized by urea assisted microwave combustion method. Structural, vibrational, morphological, optical and magnetic properties were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), UV-visible diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy, and vibrating sample magnetometry (VSM) respectively. The XRD studies showed that the samples have pure cubic spinel phase, which is further validated by Rietveld refinement. The average crystallite size is of the nanoparticles estimated using Debey-Scherrer's method was found to be in the range of 14-17 nm. The lattice parameter is increased from 8.089 to 8.160 Å with increasing in Mn2+ content. The William-Hall (W-H) analysis was used to study the effects of lattice strain over the crystallite size. Increase in lattice parameter and increase in porosity were observed on increasing Mn2+ concentration FTIR spectra showed the vibrational stretching frequencies corresponding to the zinc aluminate spinels. The morphology of the samples depicted the formation of well developed nano-sized clusters with homogeneous well crystallized grains without any agglomerations. The optical band gap value of undoped zinc aluminate nanostructure is higher than the reported bulk zinc aluminate. The direct band gap estimated using Kubelka-Munk method decreased with increasing Mn2+ content (5.05-3.49 eV), due to the formation of sub bands in the energy gap. The photoluminescence characteristics of undoped and Mn2+ doped zinc aluminates are suggestive of defect controlled process and had an effect on the luminescence. Magnetic measurements revealed that the undoped ZnAl2O4 has diamagnetic behavior while the Mn2+ doped ZnAl2O4 system has superparamagnetic behavior. © 2014 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

Structural, optical and magnetic properties of Zn1−xMnxAl2O4 (0⩽x⩽0.5) spinel nanostructures by one-pot microwave combustion technique

Pure and cobalt doped zinc ferrites were prepared by microwave combustion method using L-arginine as a fuel. The prepared samples were characterized by various instrumental techniques such as X-ray powder diffractometry, high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis, Fourier transformed infrared (FT-IR) spectroscopy, photoluminescence spectroscopy and UV-Visible diffuse reflectance spectroscopy. Vibrating sample magnetometry at room temperature was recorded to study the magnetic behavior of the samples. X-ray analysis confirmed the formation of zinc ferrites normal spinel-type structure with an average crystallite sizes in the range, 25.69 nm to 35.68 nm. The lattice parameters decreased as cobalt fraction was increased. The HR-SEM images showed nanoparticles are agglomerated. The estimated band gap energy value was found to decrease with an increase in cobalt content (1.87 to 1.62 eV). Broad visible emissions are observed in the photoluminescence spectra. A gradual increase in the coercivity and saturation magnetization (Ms were noted at relatively higher cobalt doping fractions. Copyright © 2015 American Scientific Publishers All rights reserved.

Journal of Nanoscience and Nanotechnology

Synthesis and Characterization of Cobalt Substituted Zinc Ferrite Nanoparticles by Microwave Combustion Method

Dye-sensitized solar cells (DSSCs) based on ZnO nanostructures with two different morphologies, such as nanowires (ZNWs) and nanoparticles (ZNPs), were synthesized by microwave combustion (MCM) and conventional combustion (CCM) method. The obtained ZnO nanostructures were characterized by X-ray diffraction (XRD), high resolution scanning electron microscopy (HR-SEM), high resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), diffuse reflectance (DRS) and photoluminescence (PL) spectroscopy. The XRD results confirmed the formation of hexagonal wurtzite ZnO. The crystallite size of the ZnO nanostructures was calculated using Sherrer's formula. The formation of ZNWs and ZNPs was confirmed by HR-SEM and HR-TEM. The optical absorption and PL emissions were determined by DRS and PL spectra respectively. ZnO nanostructures with band gap energies of 3.36 eV (MCM) and 3.25 eV (CCM) were obtained. The dye-sensitized ZnO nanowire arrays exhibit much stronger optical absorption as compared with ZnO nanoparticle arrays, suggesting that the larger surface area improves light harvesting. The dye-sensitized solar cell based on the optimized ZnO nanowires array reaches a conversion efficiency of 1.73%, which is higher than that obtained from ZnO nanoparticles (0.69%) under the light radiation of 1000 W/m2. As-prepared ZNWs have potential applications in fabricating next generation nanodevices.

Comparative Investigation of Structural, Optical Properties and Dye-Sensitized Solar Cell Applications of ZnO Nanostructures

A simple and rapid microwave-assisted combustion method was developed to synthesize CdO nanospheres (CNS). The study suggested that the application of microwave heating to produce the homogenous CNS was achieved in a few minutes. The structure and morphology of the as-prepared CNS were investigated by means of X-ray diffraction (XRD), Fourier transforms infrared spectra (FT-IR), high resolution scanning electron microscopy (HR-SEM), Energy Dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), diffused reflectance spectroscopy (DRS) and Photoluminescence (PL) spectroscopy. The XRD confirmed the formation of face centered cubic structure of CdO. The formation of CdO phase is also confirmed by FT-IR. The formation of spherical hollow nanospheres was confirmed by HR-SEM and TEM and their possible formation mechanisms were also tentatively proposed. The optical properties were determined by DRS and PL spectra. © 2011 Elsevier B.V.

Powder Technology

Simple and rapid synthesis of Cadmium Oxide (CdO) nanospheres by a microwave-assisted combustion method

Journal of Colloid and Interface Science

Alteration of magnetic and optical properties of ultrafine dilute magnetic semiconductor ZnO:Co2+ nanoparticles

Materials Chemistry and Physics

Structure and deep ultraviolet emission of Co-doped ZnO films with Co3O4 nano-clusters

Influence of Co-doping on the thermal, structural, and optical properties of sol–gel derived ZnO nanoparticles

The Journal of Physical Chemistry C

Optical Properties of a ZnO/P Nanostructure Fabricated by a Chemical Vapor Deposition Method

Small

Nanoscale Forces and Their Uses in Self-Assembly

Studies on the structural and optical properties of zinc oxide nanobushes and Co-doped ZnO self-aggregated nanorods synthesized by simple thermal decomposition route

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ISSN	0025-5408
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