In the present research, NiO-GDC nano-composite and Ni-GDC cermet are studied comparatively. The change in microstructure and conductivity before and after reduction has been reported. NiO-GDC nano-composite samples are prepared by solution combustion synthesis. As-synthesized powders are reduced in H-2 atmosphere at 500 degrees C for 5 hr. These samples are characterized by XRD and FE-SEM to confirm phase purity and microstructure respectively. The conductivity measurement of both NiO-GDC and Ni-GDC samples is measured by two probe and four probe method respectively. Drastic change in conductivity is observed after reduction of NiO-GDC to Ni-GDC. (C) 2020 Elsevier Ltd. All rights reserved.

An anode is a bottleneck of Solid Oxide Fuel Cells technology. In the present study anode-supported structures comprising NiO-GDC nanocomposite as an anode and gadolinia-doped ceria (GDC) of composition Gd0.1Ce0.9O1.95 thin film as electrolyte were fabricated. NiO-GDC/GDC structure is known as half cell and it is used for intermediate temperature Solid Oxide Fuel Cell (IT-SOFC). Half cell was characterized by XRD, SEM and impedance spectroscopy.

The large amount of graphene oxide was prepared by modified Hummers method, and which was then characterized by FT-Raman, FT-IR spectroscopy. Also the supercapacitor behavior of graphene oxide was studied ionic liquid. Here we observed that the graphene oxide shows best supercapacitor behavior in ionic liquid.

Solution combustion synthesis technique is one of the novel techniques used to prepare nanoparticles, multi-component ceramic oxides and nanocomposites with properties better than conventionally prepared one and these materials have been used for various applications such as sensors, catalysts, and materials for solid oxide fuel cell (SOFCs). In the present work, the method has been used to prepare nanoparticles of 10 mol% Gd doped ceria (GDC) and Cu and its oxides. The oxidant to fuel (O/F) ratio is found to affect the powder properties and even compositional homogeneity. In glycine-nitrate combustion synthesis of GDC, as revealed by XRD studies, phase pure nanoparticles with crystallite size in the range 9-12nm were obtained for all the O/F ratios. TEM measurements of calcined powder showed hexagonal shaped particles of roughly 20nm size. The exothermicity was increased with the oxidant to fuel ratio resulting in high surface area and soft agglomerates. A slightly lean O/F ratio gives surface area of 73 m2/g and soft agglomerates (D50= 5.34 mm), which eventually results into high sintering density at low temperature. Raman Spectra of GDC showed a sharp and intense peak at 467 cm−1which corresponds to CeO2due to F2gsymmetry of the cubic phase. In combustion synthesis of copper nitrate and citirc acid, the compositional homogenity and phase purity was affected by the oxidant to fuel ratio. The combustion at stoichiometric O/F ratio gives Cu nano particles, lean O/F ratio gives nanoparticles of Cu, CuO and Cu2O and rich ratio gives pure CuO nanoparticles. These nanoparticles have been studied with different characterization techniques like XRD, TG-DTA, SEM, TEM, FT-IR and Raman.

The crack free nanocrystalline, La0.6Sr0.4Co0.2Fe0.8O3 (LSCF) membrane with high in plane conductivity have been successfully deposited on dense Ce0.9Gd0.1O1.95 (GDC) by the Spray Pyrolysis Technique (SPT). The film with nominal 1μm thickness, get crystallizes on annealing at 800°C for 4 hrs. The effect of deposition temperature on microstructure, crystallization and conductivity has been systematically studied. The film deposited at 300°C shows higher in plane conductivity of 26.6 SCm-1 with activation energy of 0.23 eV over the range of 400°C-800°C. The higher conductivity attributed towards the uniform, thin & dense microstructure of deposited film which is clarify from Scanning Electron Microscope (SEM) images. No interfacial reaction product between LSCF and GDC were detected from X-ray diffraction (XRD) studies upon annealing at 800°C.

Solution combustion synthesis technique is one of the novel techniques used to prepare nanoparticles, nanocomposite and ceramic oxides. The authors prove in this study the usefulness of the technique in producing copper nanoparticles. In solution combustion, the stoichiometric ratio, according to propellant chemistry, needs the oxidiser-to-fuel ratio to be unity. The combustion of cupric nitrate and citric acid at stoichiometric ratio results in copper nanoparticles. The copper nanoparticles were characterised by different techniques, such as X-ray diffraction, thermal gravimetry/differential thermal analyser, Fourier transform infrared, FT-Raman and scanning electron microscopy. The Cu nanoparticles get oxidised to Cu2O slowly at 250 degrees C and to CuO at 530 degrees C. The combustion of the reactants with lean and rich oxidant-to-fuel ratio (O/F) ratios results in mixed phases except in the 1:0.71 ratio. The phases in lean O/F ratios were Cu, CuO, Cu2O, whereas only CuO was present in rich O/F ratios.

In the present work, systematic study of series of NiOx GDC(1−x) where x=0.1–0.6; has been reported for the first time. For the synthesis of homogeneous NiO–GDC nanocomposite powders, the nano-powders of NiO and Ce0.9Gd0.1O1.95 (GDC10) synthesized by solution combustion synthesis were mixed in mol % proportion. NiO–GDC nanocomposite can be reduced in situ to form Ni–GDC cermet anode. Hence the Ni–GDC cermet anode combines the catalytic activity and high electronic conduction property of Ni and ionic conductivity of GDC. Nano-crystalline constituents in the NiO–GDC nano composite are believed to give better anodic performance than microcrystalline constituents. Hence the efficient study of the atomistic structure and the accurate characterization of the structural parameters, such as crystallite size and internal strains, are of considerable interest. Therefore the NiOx–GDC101−x nanocomposite powders were characterized by XRD and FTIR spectroscopy. Further these powders were pelletized, sintered and characterized by FE-SEM and d.c. conductivity.

In recent years, doped ceria is an established and promising candidate as solid electrolyte for intermediate temperature solid oxide fuel cell (IT-SOFC). In this investigation, synthesis and characterizations of nano-crystalline Gd doped ceria, (Ce1-xGdxO2-x/2, where x = 0-0.3), prepared using glycine-nitrate process (GNP) has been presented. Evolution of structural and morphological properties of nano-powders as a function of heat treatment has also been studied. The prepared samples were characterized using TG-DTA, FT-IR, Raman spectroscopy, XRD, SEM, etc. In addition, the effect of Gd content over the micro-structural properties of nano-crystalline Gd doped ceria was investigated. Raman analysis of calcined powders confirms the formation of the solid solution of Ce1-xGdxO2-x/2 instead of mixture of CeO2 and Gd2O3. The solid solutions obeyed Vegard's rule very well. Grain growth of sintered samples was observed to hinder with an increase in Gd content. (c) 2010 Elsevier B.V. All rights reserved.