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Synthesis of SrFe(Al)O3−δ–SrAl2O4 nanocomposites via green route

Abstract:

A ceramic nanocomposite of SrFe(Al)O<inf>3−δ</inf> and Sr<inf>3</inf>Al<inf>2</inf>O<inf>6</inf> was obtained using the controlled combustion of a previously synthesized chitosan-Sr-Fe-Al precursor. The complex formed by chitosan and metal ions in the organometallic precursor was confirmed by FTIR, TGA and DSC analysis. The nanocomposite consisted of hard agglomerates containing nanoparticles of Sr-Fe-Al oxides with oval morphology and an average diameter ≤ 9 nm. The DRX analysis indicated a composition of SrFe(Al)O<inf>3−δ</inf> and Sr<inf>3</inf>Al<inf>2</inf>O<inf>6</inf> phases. Also, HRTEM and XPS verified the formation of a principal phase of ceramic composite identified as SrFeO<inf>3–x</inf>(2.5 ≤ x ≤ 3.0) possibly of aluminum-substituted structure, and minority phases of SrAl<inf>12</inf>O<inf>19</inf> and SrAl<inf>2</inf>O<inf>4</inf>. Furthermore, a by-product of strontium carbonate was found as traces on the composite oxide surface. It was attributed to solid-gas reactions of strontium oxide with carbon dioxide, the latter produced during the oxidative decomposition of the biotemplate. Also, moderated calcination temperature limits the total decomposition of SrCO<inf>3</inf>.