Crystallization and decomposition of Mn1.5Co1.5O4 spinel synthesized using EDTA gel processing

A manganese–cobalt (Mn1.5Co1.5O4) spinel compound was synthesized by means of gel processing with EDTA (ethylenediaminetetraacetic acid) as a chelating agent binding Mn and Co in aqueous solutions. The phases obtained in the process were stable and formed an amorphous gel, which was then annealed in air at temperatures of up to 1153 K. Structural and thermal evolution of the product formed after the decomposition of the gel precursor at different temperatures was traced using XRD and FTIR studies as well as DSC/TG methods, respectively. The obtained results indicated that the gel precursor decomposed entirely at temperatures higher than 993 K, while the crystallization of the Mn1.5Co1.5O4 spinel with an intermediate tetragonal/cubic structure began at a temperature as low as 553 K. Both XRD and FTIR studies revealed an increasing fraction of the tetragonal phase up to 853 K and no further change at higher temperatures. Moreover, at 1033 and 1153 K FTIR studies of the material revealed partial inversion of the spinel.