Papers by Keyword: Solution Combustion

Abstract: Gamma-aminobutyric acid (GABA) is a crucial inhibitory neurotransmitter that decreases nervous system activity by inhibiting signal transmission across synapses. Imbalances in GABA levels are linked to neurological diseases. This study developed an electrochemical sensor for detecting GABA using a ZnO/GO composite as the sensing material. Graphene oxide (GO) was synthesized via a modified Hummer’s method, while nanoparticulate zinc oxide (ZnO) was prepared using a solution combustion method. X-ray diffraction and morphological analysis showed crumpled graphene oxide sheets stacked into multilayers and a single phase of wurtzite-structured ZnO with a crystallite size of 69.37 nm; however, the particles tended to cluster together into larger agglomerates, leading to a reduction in specific surface area. The ZnO/GO composite demonstrated synergistic electrocatalytic activity. Cyclic voltammetry in GABA solutions (0.1 to 1000 µM) revealed distinctive oxidation and reduction peaks with sensitivity ranged from 0.0184 to 0.6629 µA mM^-1 mm^-2. Despite moderate electrocatalytic performance, the ZnO/graphene oxide composite shows potential as a GABA sensing material.

Abstract: In this work, solution combustion processed titanium, zinc co-doped indium oxide high transparent semiconducting thin films were demonstrated at annealing temperatures of 300, 350 °C. In the process, low-temperature combustion at 123 °C was verified through thermogravimetric analysis; acetylacetone, 2-methoxyethanol served as fuel and solvent respectively in the redox reaction. Indium titanium zinc oxide (ITiZO) films were developed on glass substrates by spin coating followed by annealing at different temperatures. ITiZO films, powder exhibited high crystallinity exactly matching with indium oxide peaks without forming secondary phases. But, the presence of In, Ti, Zn, and O is clearly visible on film through energy dispersive spectroscopy. Films had transparency more than 85% in the visible range with optical band gap ranging 3.8-3.9 eV. These ITiZO films with smooth and low roughness ranging 0.46-0.5 nm, can have a potential application as an active layer in transparent thin film transistors and optoelectronic devices.

Abstract: Barium strontium calcium titanate is a dielectric material exploited in fabrication of electronic devices such as capacitors, signal filters and satellite components. Dielectric properties can be enhanced through compositional and microstructural control. This study, therefore, aimed at synthesizing barium strontium calcium titanate (Ba_0.05Sr_xCa_0.95-xTiO₃, where x = 0, 0.225, 0.475, 0.725 and 0.95) powders by a solution combustion technique. The powders were pressed, sintered at 1450°C and tested for their properties. Experimental results revealed that strontium content did not significantly influence chemical composition, particle sizes and density. All powders exhibited a single phase corresponding to Ba_0.05Sr_xCa_0.95-xTiO₃ with fine particles with the average size smaller than 0.4 micrometer. All sintered samples had density higher than 95% of theoretical density. On the contrary, the results indicated that strontium content affected grain size, grain morphology and dielectric constant of the sintered samples. The highest dielectric constant of 531 (at 1 MHz) was achieved in the Ba_0.05Sr_0.225Ca_0.725TiO₃. Dielectric constant was discussed with respect to microstructure.

Abstract: Utilization of photocatalytic properties of materials can be perceived through a wide range of applications, such as anti-bacterial, water treatment, and self-cleaning materials. It has been established that doping can result in alteration of photocatalytic activities. This study aimed at studying effects of tin concentration on chemical composition, microstructure, band gap energy, and photocatalytic activities of tin-doped titanium dioxide powder synthesized by solution combustion technique. Experimental results revealed that concentration of tin significantly influenced chemical composition of the powders. A semi-quantitative analysis indicated that tin oxide secondary phase increased from 11 to 23 wt%, as the Sn increased from 2.5 to 10 mol%, respectively. Tin concentration, nevertheless, did not significantly influence microstructure of the powders. All powders had average particle size ranging from 13.1 to 13.4 nm, which agglomerated into clusters with average sizes ranging from 103 to 140 nm. A slight increase of band gap energy was observed at higher tin concentration. The most prominent photocatalytic activities, determined from decomposition of methylene blue, was found in the titanium dioxide powder with 2.5 mol% Sn.

Abstract: Nanocrystalline yttria powders were successfully synthesized by microwave-induced solution combustion method using a binary yttrium salt system with yttrium nitrate as oxidant and yttrium acetate as reductant. The process involved the redox reaction between the two yttrium salt under the heat generated by absorbing microwaves. The prepared powders were characterized by X-ray diffraction (XRD), Fourier Transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM) to study the structure and powder morphology. The prepared powders were indicated to exhibit single-phase cubic crystalline yttria structure. The oxidant/reductant ratios and the calcination temperatures had an effect upon the particle size and powder morphology. The size of the crystallites varied in the range of 16 nm~27 nm with different reductant proportion. The powders were observed to show loosely agglomerated fractals.

Abstract: Zinc Ferrite (ZF) nanopowders relatively uniform size distributions ranging from 5 to 14 nm were prepared by solution combustion and hydrothermal methods. The PXRD showed cubic phase, spinel structure, and particle size in nanoscale. The SEM images confirm the agglomeration of the product composed of uniform nanoparticles of flakes type and spherical type in combustion and hydrothermal methods respectively. The purity check was done by FTIR. The optical band gap energy (Eg) obtained by UV-Vis spectra of the ZF nanopowders prepared by solution combustion and hydrothermal methods were found to be 1.985 eV and 1.99 eV respectively. The present study clearly shows that the distribution of the cations within the spinel lattice of the ferrite nanoparticles are strongly affected by the synthesis method used. Results suggest that the electrical properties depend on the particular method of preparation and sintering temperature of the prepared samples. The resistivity of the samples increased to the order of 103 by sintering the samples. It is observed that the activation energy (Ea) decreases with increasing the sintering temperature.

Abstract: Ultrafine cerium-doped GSAG phosphor powders are prepared by a solution combustion process using glycine and urea as fuel. Single-phase cubic GSAG:Ce crystalline powder is obtained by calcining the as-synthesized amorphous materials at 800oC and no intermediate phase is observed. Transmission electronic microscope morphology shows that the resultant GSAG:Ce powders have uniform size and good homogeneity. The photoluminescence spectra of Ce3+ substituted for Ce3+ in GSAG has been measured on samples calcined at 1000oC.