The influence of K substitution on the structural, optical and magnetic properties of LaFeO3 perovskites

Abstract

Single-phase lanthanum ferrite oxides doped potassium (K) with various composition of La1-xKxFeO3 (0.0≤ x ≤ 0.3) were successfully prepared using cost-effective precursors via a solid-state reaction route. The influence of K substitution at La site of LaFeO3 on its structural, optical, and magnetic properties have been studied. X-ray diffraction (XRD) results indicated that all synthesized samples were a polycrystalline single-phase orthorhombic perovskite structure, with peaks shifting to higher Bragg angles by increasing K amount. Direct bandgap energy (Eg) of La1-xKxFeO3 samples was dramatically decreased from 2.28 eV to 1.22 eV with increasing the amount of K substitution in the LaFeO3 Lattice. Magnetic hysteresis loops show that the obtained samples have a ferromagnetic response at room temperature with enhanced magnetization from 0.16 to 1.72 emu/g with increasing the K concentration. The changes of the optical and magnetic properties attributed to the crystal structure defects resulting from the replacement of La3+ by K1+, which cerate oxygen vacancies due to the variation in the valence state ratio of Fe4+/Fe3+. The enhanced magnetization and tunable Eg in the visible region make La1-xKxFeO3 (0.0≤ x ≤ 0.3) promising materials for environmental applications such as solid oxides fuel cells (SOFC) and photocatalysis.