Herein, a citric acid combustion method is used to prepare LaFeO3 (LFO) and LaFe0.5Cr0.5O3 (LFCO). Stable and distorted perovskite structures are detected by X-ray diffraction (XRD) patterns of both samples. Due to the substitution of chromium ions, Fe-Fe couplings are wholly disrupted, thus indicating the transition from a sextet to a singlet at room temperature. The M versus T curve of LFO exhibits two anomalous peaks related to Fe-O-Fe superexchange interactions. However, a quite different behavior is observed in LFCO. It reveals the negative irreversibility below 239 K and becomes paramagn...
