Mn Valence, Magnetic, and Electrical Properties of LaMnO_(3+δ) Nanofibers by Electrospinning

摘要

LaMnO_(3+δ) nanofibers have been prepared by electrospinning. The nearly 70% of Mn atoms is Mn~(4+), which is much higher than chat in the nanoparticles. The average grain size of our fibers is approximately 20 nm, which is the critical size producing the nanoscale eFfect. The nanofibers exhibit a very broad magnetic transition with T_c ≈ 255 K, and the T_c onset is around 310 K. The blocking temperature T_B is 180 K. The sample shows weak ferromagnetic property above the TV and below TV and superparamagnetic property near the T_c onset. The resistivity measurements show a metal-insulator transition near 210 K and an upturn at about 45 K.