Formation of Fe⁴⁺ based on the Fe-O bond lengths in perovskite Eu1-xSrxFeO₃

The physical properties of high oxidation state of transition metal oxide compounds have attracted many research interest for its potential applications. A systematic investigation of Fe 4+ in Eu 1-x Sr x FeO 3 with x = 0, 0.1, 0.2, 0.3, and 0.4 has been carried out in polycrystalline form obtained using sol-gel method. The single phase of Eu 1-x Sr x FeO 3 is observed up to x = 0.3. The X-Ray powder pattern for low Sr content of x = 0.1, is best refined by using EuFeO 3 crystal structure with Sr occupied the Eu-site. On the other hand, for higher Sr contents, two phases of EuFeO 3 and Eu 1/3 Sr 2/3 FeO 3 are required to obtained the best refinement. The result of the refinements shows that the volume and the average bond lengths of Fe-O decreases as increasing the Sr content. These results are consistent to support the existence of Fe 4+ upon Sr doping in Eu 1-x Sr x FeO 3 . For the Sr content of x = 0.1, an anomalous change of the volume is observed.