Tailorable nano MgO.xAl2O3 spinel compositions along line of homogeneity via gel combustion route: Influence on phase evolution

Publication date: Available online 11 June 2019Source: Materials Chemistry and PhysicsAuthor(s): R. Halder, S. BandyopadhyayAbstractVery fine sized (∼5–15 nm) magnesium aluminate spinel (MgO.xAl2O3) powder of different degree of solid solubility (x = 1, 1.25, 1.50, 1.75, and 2) have been attempted for synthesis following a gel combustion method to meet its high demand in the fields of refractory, photo catalysis, sensor and strategic applications, etc. Nitrates of magnesium and aluminum were used as oxidants for exothermic reactions fuelled by urea added with formaldehyde solution acting as reductant. Thermal decomposition reactions of polymer gels resulting in phases containing varied cationic ratio (Mg2+:Al3+) were investigated through DTA-TGA studies. Phase identification of synthesized powders derived from varying mole ratio of metal nitrates was performed by X-ray diffractometry (XRD) through Rietveld refinement using HighScore Plus software and was reconfirmed by Fourier Transform Infrared Spectroscopy (FTIR). Particle morphology was examined under Field Emission Scanning Electron Microscope (FESEM) & Transmission Electron Microscope (TEM). XRD pattern revealed the as-synthesized stoichiometric magnesium aluminate spinel (MgAl2O4) powder to be in amorphous state. In contrast, increasing trends in the extent of crystallinity in the as-synthesized form was obvious for alumina richer compositions. Dependence of development of crystallinity was explained in the li...
Source: Materials Chemistry and Physics - Category: Materials Science Source Type: research