Preparation and powder characterization of spinel-type CoxNiMn2-xO4 (0.2≤x≤1.2) by the ethylene glycol-metal nitrate polymerized complex process

CoxNiMn2-xO4 (0.2 less than or equal to x less than or equal to 1.2) spinel-type powders were prepared by auto-combustion of ethylene glycol-metal nitrate polymerized gel precursors, and the thermal behaviour of the different samples was independent of the chemical composition. The formation of a pure spinel-type phase, with no intermediate compounds, was attained from the burning of the polymerized gel precursor and subsequent calcining at 600-700 degreesC. The formation and the microstructural evolutions of the spinel-type phase have been studied by Fourier transform infrared (FTIR) spectroscopy, simultaneous thermogravimetric and differential thermal analysis (TG/DTA), X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Powder characteristics such as particle size and specific surface areas of the calcined powders were dependent of the chemical compositions. In the same way, the crystalline structure of the synthesized spinel-type phases were strongly dependent of the Co content. (C) 2003 Elsevier Ltd. All rights reserved.