Thermogravimetric and Magnetic Studies of the Oxidation and Reduction Reaction of SmCoO$_{3}$ to Nanostructured Sm$_{2}$O$_{3}$ and Co

The SmCoO$_{3}$ to nanostructured Sm$_{2}$O$_{3}$ and Co oxidation and reduction reaction has been studied by thermogravimetric analysis (TGA) measurements in forming gas (FG) and inert N$_{2}$ atmospheres, x-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The TGA measurements showed two clearly resolvable reduction processes when heating in FG, from the initial SmCoO$_{3}$ phase through an intermediate nanostructured mixture of Sm$_{2}$O$_{3}$ and CoO when heated to 330\textdegree C for several minutes, and then the conversion of CoO to metallic Co when heated above 500\textdegree C. These phases were confirmed by XRD and VSM. Similar measurements in N$_{2}$ yielded little mass change below 900\textdegree C and coupled reduction processes at higher temperatures. Isoconversional measurements of the CoO to Co reduction reaction in FG yielded activation energies above 2eV/atom in the nanostructured system. This value is several times larger than those reported in the literature or obtained by similar measurements of bulk mixtures of Sm$_{2}$O$_{3}$ and CoO, suggesting the nanostructuring was the source of the large increase in activation energy.