Copper aluminate nanostructured materials were synthesized by a microwave combustion method (MWCM) using the plant extract (aloe vera) as a fuel without using any other template or surfactant. For comparison, it was also prepared by using the conventional combustion method (CCM). The as-synthesized copper aluminate was characterized by powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), diffuse reflectance spectroscopy (DRS), photoluminescence (PL) spectroscopy, nitrogen adsorption/desorption isotherms, and vibrating sample magnetometer (VSM). The results indicated that the copper aluminate nanomaterials obtained by MWCM shows good crystallinity with the uniform size distribution than the ones prepared by CCM. The XRD and FT-IR results confirmed the crystal structure of copper aluminate. The formation of copper aluminate nano- and microstructures were confirmed by HR-SEM. The optical absorption and photoluminescence emissions were determined by DRS and PL spectra, respectively. The effect of the catalyst and the oxidant on the catalytic oxidation of benzyl alcohol was also investigated. © 2014 Elsevier Ltd.

John Kennedy L

Physics

School of Advanced Sciences

Chennai Campus

Ragupathi C

Vijaya J.J

Bououdina M.

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 Science in Semiconductor Processing

In this study, bismuth doped copper aluminate (CuAl2-xBixO4 x = 0, 0.01, 0.03, 0.05 and 0.10) nanoparticles were prepared via the solution combustion method and characterized by numerous procedures like powder X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, diffuse reflectance spectroscopy (DRS), scanning electron microscopy equipped with energy dispersive X-ray analysis (SEM-EDAX) and vibrating sample magnetometer (VSM). UV–Vis spectra exhibit low band gap energy ranging from 1.77 to 1.88 eV for the synthesized semiconductor oxide nanoparticles. The photocatalytic activity of copper aluminate and bismuth doped copper aluminate nanoparticles was studied by performing the decomposition of organic pollutants such as Methylene blue and Rhodamine-B under UV-light and visible light. It has been noticed from the results that the highest degradation was observed for Methylene blue dye with the bismuth doped copper aluminate (CAB03) nanoparticles compared to Rhodamine B. 99.71% degradation of Methylene blue was obtained within 60 min under UV-light irradiation and 99.90% within 60 min under visible light (H2O2) with 25 mg of catalyst. © 2017 Elsevier B.V.

Materials Chemistry and Physics

Structural, optical, magnetic and photocatalytic properties of bismuth doped copper aluminate nanoparticles

In this paper, a simple and economic route for the preparation of CuAl2O4 is proposed. The method was developed with the objective of obtaining a material with greater surface area, when compared to the spinel prepared by conventional combustion method (CCM). The catalytic properties of CuAl2O4 spinel prepared by CCM are compared with the one prepared microwave combustion method (MCM). Nano-sized CuAl2O4 were synthesized by both CCM and MCM using Opuntia dillenii haw as the plant extract, and were characterized by X-ray diffraction analysis (XRD), high resolution scanning electron microscopy (HR-SEM), N2 adsorption/desorption isotherms, and diffuse reflectance spectroscopy (DRS). Oxidation to their corresponding carbonyl compounds, high selectivity, and inexpensive precursors make this catalytic system a useful oxidation method for benzyl alcohol. The XRD results confirmed the formation of a cubic CuAl2O4. The formation of CuAl2O4 nanorices and nanorods structures were confirmed by HR-SEM. Through MCM method, CuAl2O4 (sample B) with a high specific surface area of was obtained. The band gap values of the (2.30 and 2.35 eV) for the obtained oxides are due to the nanometric dimensions of the nanostructures. The effect of the solvent, temperature, and oxidant on the oxidation of benzyl alcohol is reported. © 2014 Elsevier B.V. All rights reserved.

Journal of Molecular Structure

Selective liquid phase oxidation of benzyl alcohol catalyzed by copper aluminate nanostructures

Ceramics International

Combustion synthesis, structure, magnetic and optical properties of cobalt aluminate spinel nanocrystals

The present study reports a green chemistry approach for the biosynthesis of nano-zinc aluminate by a microwave method using high purity metal nitrates and aloe vera plant extract. Aloe vera extract simplifies the process and provides an alternative process for a simple and economical synthesis of nanocrystalline zinc aluminate. It is prepared by conventional and microwave method by with and without using the plant extract for comparison purpose. The obtained nanomaterials were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), high resolution scanning electron microscopy (HR-SEM), energy dispersive X-ray analysis (EDX), high resolution transmission electron microscopy (HR-TEM) diffuse reflectance spectroscopy (DRS) and photoluminescence (PL) spectroscopy. The XRD confirmed the formation of cubic structure of zinc aluminate. The formation of zinc aluminate phase is also confirmed by FT-IR. The change in morphology from nanorods to nanosheets from the conventional method to microwave method is clearly shown by HR-SEM. The optical properties were determined by DRS and PL spectra. © 2013 The Society of Powder Technology Japan. Published by Elsevier B.V.

Advanced Powder Technology

A new approach: Synthesis, characterization and optical studies of nano-zinc aluminate

The effect of ethylenediamine addition in the sol-gel method for the preparation of nano CuAl 2O 4 spinel for the enhancement in their structural, electrical, optical and catalytic properties was investigated. The samples were prepared by two different methods: sol-gel and modified sol-gel technique using ethylenediamine. X-ray diffraction (XRD), Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM), high resolution-transmission electron microscopy (HR-TEM), energy dispersive X-ray analysis (EDX), nitrogen adsorption/desorption isotherms, temperature dependent conductance measurements, thermoelectric power (TEP) measurements and UV-visible diffuse reflectance (UV-vis-DRS) spectra were used to characterize the samples prepared. CuAl 2O 4 prepared by modified sol-gel technique was found to possess a higher surface area, lower crystallite size, lower activation energy and high porosity than the one prepared by sol-gel method which in turn lead to the improved performance of it towards the selective oxidation of benzyl alcohol to benzaldehyde. Effect of solvent on the catalytic oxidation of benzyl alcohol by the nano CuAl 2O 4 prepared by modified sol-gel technique was also investigated. © 2012 Elsevier B.V. All rights reserved.

Journal of Alloys and Compounds

Comparative study of nano copper aluminate spinel prepared by sol–gel and modified sol–gel techniques: Structural, electrical, optical and catalytic studies

Polycrystalline MgCuZn ferrites with chemical formula Mg 0.50-xCuxZn0.50Fe2O4 (x = 0.00, 0.05, 0.10, 0.15, 0.20, 0.25 and 0.30) were prepared by microwave sintering method. These powders were calcined, compacted and sintered at 950 °C for 30 min. Structural, microstructural and elemental analyses were carried out using X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray spectrometry (EDS), respectively. The lattice parameter is found to increase with increasing copper content. A remarkable densification is observed with the addition of Cu ions in the ferrites. The sintered ferrite was characterized for initial permeability, dielectric constant and dielectric loss tangent and ac conductivity measurements. The temperature variation of the initial permeability of these samples was carried out from 30 °C to 200 °C. The dielectric constant, dielectric loss tangent and ac conductivity have been measured in the frequency range of 100 Hz to 1 MHz. Initial permeability and dielectric constant were found to increase and dielectric loss decreased with Cu substitution for Mg, up to x = 0.20. The ferrite powder prepared is suitable for the application in multilayer chip inductor due to its low-temperature sinterability, good magnetic properties and low loss at high frequency. © 2010 Elsevier B.V.

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ISSN	1369-8001
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