Advanced Materials Research Vol. 938

Abstract: Electrodeposition is known as a simple and low-cost method to synthesize good-quality coating with excellent hardness. In this work, the morphology changes on Cobalt coating with the addition of iron and nickel elements were investigated. Co (Cobalt) and Co-based alloy coatings were prepared by electrodeposition technique using sulfate-based electrolytes. The process was conducted at 50^°C temperature in an acidic environment (pH 3). The pure Co coating shows the tendency to form snowflake-like morphology structure. The dendritic morphology appeared in the Co-Fe coatings. However, the dendritic morphology was totally disappeared in the Co-Ni-Fe morphology and replaced by spherical morphology. The crystal structure of Co-Ni-Fe coating changed from bcc into mixed bcc+fcc structure with the addition of Ni element in Co-Fe composition. The Ni element which had been introduced in the Co-Fe composition improved the surface morphology and reduced the average particle size. The surface morphologies in the coatings affect the particles size and hardness property. This may due to the formation of full, compact coatings morphology and introduction of particles boundaries interphase. The Co-Ni-Fe coating with smaller particle size, less void formation and mixed crystal structure of bcc+fcc was roughly two times harder than pure Co.

Abstract: Multi-wall carbon nanotube (MWCNT) structures were grown on cobalt catalyst layer through Plasma Enhanced Chemical Vapor Deposition (PECVD) process. Acetylene (C2H2) and hydrogen (H2) are used as precursors during the PECVD process. The morphology structures of the MWCNTs grown under different PECVD time were investigated and characterized using Scanning Electron Microscope (SEM). The effect of the PECVD time on the MWCNT growth is studied by varying the PECVD time at 45 sec and 600 sec. The morphology structures suggest that the growth rate is proportional to the PECVD time under the similar setting condition of pressure, acetylene flow-rate and temperature.

Abstract: Single phase polycrystalline with = 0, 0.01 and 0.02 were synthesized by conventional solid state reaction method. The X-ray diffraction shows that the ceramic samples has hexagonal Wurtzite structure with a space group of p6₃mc and average crystallite size in the range 52 - 88 nm. The dielectric and electrical properties were studied within the temperature range 30 °C to 500 °C under air atmosphere as function of frequency (10 kHz). The electrical properties of grain interior and grain boundary have been studied by using the impedance spectroscopy and follow the non-Debye relaxation process. It was observed that the AC conductivity of ceramic samples following the Universal power law within the frequency range 1kHz to 1 MHz. The activation energy of Pure is 0.29 eV was calculated by using the Arrhenius-relation with in temperature range 300 - 500 °C, which is increased to (0.40 eV ) when = 0.02 of at 10 kHz . The peaks attributed at 1415 cm^-1 () and 1413 cm^-1 () in FT-IR measurement of are due to Ca-O stretching from the calcite phase of CaCO₃, which is not observed in Pure ZnO confirms the presence of Ca in ZnO lattice. Keywords: , FT-IR, Impedance spectroscopy, ac conductivity, Dielectric constant.

Abstract: Zinc oxide nanostructures have been done by many scientists but amongst the soft chemistry methods, chelating agents are normally used. In this work zinc oxide nanostructures have been synthesized using a soft chemistry method without using a chelating agent. The precursor were annealed at various temperatures of 400 °C, 500 °C, 600 °C, 700 °C, 800 °C and 1200 °C for 24 h. Nanostructures are found with rod-like shapes and they are compared with larger oval morphology. X-Ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), and UV-Vis spectroscopy were used for characterization. XRD results confirm that all peaks were pure and single phase without the presence of any impurities. It was found from electron microscopy results that the morphology of the materials annealed at 400 °C possesses nanorod shape and as the calcination temperature increases, the material consists of mixed rod, spherical and oval shapes. The aspect ratio of the materials decreases when the annealing temperature increases. The absorption edges of the materials annealed at higher temperatures show a red-shift implying that narrowing of the band gaps occur in the materials. Band gap were evaluated and found to be between 3.32 to 3.19 eV.

Abstract: Silicon nanoparticles (Si-NPs) were synthesized using thermal plasma assisted gas phase condensation at different compositions of argon and hydrogen. The content of hydrogen in argon was varied from 0 to 15 mole percent. Synthesized nanoparticles were characterized by Transmission Electron Microscopy (TEM) and Fourier Transform Infrared spectroscopy (FTIR). Noticeable change in the morphology of nanostructures was observed with changing hydrogen content. Si-NPs synthesized in the presence of argon consisted of flake like structures, mostly amorphous. With increase in hydrogen concentration, flake like structures disappeared and prominent spherical structures and nanowires were observed. On further increasing hydrogen content spherical crystalline nanostructures with a tail of nanowire were formed and then nanoplatelets of SiC along with silicon nanostructures were observed. Different parameters that changed owing to different hydrogen concentration, were calculated and it is attempted to predict the cause of changing morphology.

Abstract: In the present work, we have reported the effect of cobalt concentration on Bi_0.95Ba_0.05Fe_1-xCo_xO₃ (where x = 0.01, 0.03, 0.05) synthesis by solvothermal method. The structural properties are studied using X-ray diffraction by performing Rietveld analysis. The change in magnetic properties is associated with bond angle. The leakage current density mechanism is studied by measuring I-V characteristics.

Abstract: This study focuses on the preparation and characterization of Nickel oxide nanoparticles (NiONPs) supported on the reduced graphene oxide (r-GO) surface by a simple ultra-sonochemical method (r-GO-NiONPs). The formation of the r-GO was confirmed by FT-IR spectroscopy. The layer content of the r-GO was characterised by Raman spectroscopy. The crystalline nature and average particle size of the NiONPs were inferred by Powder-XRD spectroscopy. The surface morphology of the prepared nanoparticle was studied by the Scanning Electron Microscopy (SEM). The total surface area of the r-GO-NiONPs was ascertained by Nitrogen gas BET adsorption isotherm. Surface area of r-GO-NiONPs is 282 m²g^-1 which is little over twice of Graphene Oxide (GO) 132 m²g^-1. The magnetic properties of the prepared r-GO-NiONPs was studied using Vibrating Sample Magnetometer (VSM). Field dependent magnetization studies of r-GO-NiONPs delivers a very promising result.

Abstract: The Nitrogen doped graphene oxide (NGO) was synthesized by doping N-atoms on graphene oxide (GO) sheet by using melamine which serves as the nitrogen source, through hydrothermal approach. The insertion of nitrogen atoms into the graphene oxide sheet was confirmed by FT-IR, EDS and Raman spectroscopic techniques. We also probed into the tuned dielectric and magnetic properties of NGO due to the decomposition of oxy functional groups of GO and the insertion of pyridinic, pyrrolic and graphitic type nitrogen atoms into the graphitic structure. The dielectric properties were measured by Broadband Dielectric Spectroscopy (BDS). The magnetic behaviour of the sample was demonstrated by Vibrational Scanning Magnetometer (VSM).

Abstract: Nickel oxide has been widely used as material for antiferromagnetic, electrochromic display and functional layer for chemical sensors. Nickel oxide thin films of various molarities were deposited using a simple nebulizer technique and the substrate temperature was fixed at 350C. The effect of the molarity of precursor solution on structural and optical properties was studied using X-ray diffraction (XRD) and UV-Vis-NIR spectrometer techniques respectively. The band gap of the material was confirmed by photoluminescence spectrometer. It is found that increase in the molarity of 10ml volume of the sprayed solution leads to the increasing in film thickness. X-ray diffraction studies indicated cubic structure and the crystallites are preferentially oriented along (1 1 1) plane. It is also found that as the concentration of the solution increases the transmittance decreases, consequently the band-gap energy wanes from 4.0 eV to 3.2 eV.

Abstract: xNd₂O₃-35LiCl-(30-x)PbO-35ZnO glasses (where x=0.1, 0.2, 0.3, 0.4 and 0.5 mol %) were prepared by melt quenching method and converted to glass ceramics by controlled crystallization processes. Glass and glass ceramic phases were confirmed by XRD. The electrical conductivity of these samples has been carried out as a function of frequencies at different temperature. Ac conductivity data of these glasses has been analyzed using a single power law. The exponents obtained from the power law fits is found to be in the range from 0.2 0.3 in these glass ceramics and shows moderate temperature dependence. The stretched exponent β also is seen to vary slightly with temperature. Scaling behavior also has been carried out using the reduced plots of conductivity and frequency. The time-temperature superposition of data points is found to be satisfactory indicating that the ion transport mechanism decreases with annealing temperature and increase with compositions studied. Activation energy (E_a) has been calculated for all the samples at different temperatures, is found to vary in the range of 0.4eV to 0.5eV.