Effect of Mn doping on particulate size and magnetic properties of LaFeO^sub 3^ nanofiber synthesized by electrospinning

Ultrafine one-dimensional LaFe1-xMnxO3 (0.00 ≤ x ≤ 0.15) nanofibers were prepared by electrospinning. The X-ray diffraction pattern of Mn-doped LaFeO3 nanofibers showed orthorhombic perovskite crystalline structure of LaFeO3. Transmission electron microscopy (TEM) images revealed that the nanofibers were composed of fine particulates with diameter of about 50 ± 5 nm in pure LaFeO3 and 35 ± 5 nm in 15 mol% Mn-doped nanofibers. The chemical state of Mn3+ and Mn4+ in Mn-doped LaFeO3 nanofibers were confirmed from curve fitting after X-ray photoelectron spectroscopy (XPS) measurement. The optical energy bandgap decreased with increasing Mn-doping, which can be ascribed to Mn dopant levels near the conduction band. A clear hysteresis loop can be observed for Mn-doped LaFeO3 nanofibers. With increasing Mn concentration, remnant magnetization linearly increased from 0.098 to 0.289 emu/g at 10 K, which is due to uncompensated spin moment at the surface and the differences of spin magnetic moments between Fe and Mn ions. The coercivity is decreased from 632 to 190 Oe, following an increasing trend with increase of particles size up to a critical particle size. The present work shows that Mn doping in LaFeO3 nanofibers is a very effective method for having enhancement of magnetic property in antiferromagnetic LaFeO3.