Synthesis and characterization of La_(0.8)Sr_(0.2)Co_(0.5)Fe_(0.5)O_(3+-delta) nanopowders by microwave assisted sol-gel route

摘要

Nano-crystalline La_(0.8)Sr_(0.2)Co_(0.5)Fe_(0.5)O_()3±delta) powder has been successfully synthesized by microwave assisted sol-gel (MWSG) method.The decomposition and crystallization behavior of the gel-precursor was studied by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD) analysis.From the result of FT-IR and X-ray diffraction patterns,it is found that a perovskite La_(0.8)Sr_(0.2)Co_(0.5)Fe_(0.5)O_(3±delta) was formed by irradiating the precursor at 700 W for 3 min,but the well-crystalline perovskite La_(0.8)Sr_(0.2)Co_(0.5)Fe_(0.5)O_(3+-delta) was obtained at 700 W for 35 min.Morphological and specific area analysis of the powder were done by transmission electron microscopy (TEM),scanning electron microscope (SEM) and Bru-nauer-Emmett-Teller (BET).The surface areas measured was 38.9 m2/g and the grain size was ~23 nm.Electrochemical properties of pure LSCF cathode on YSZ electrolyte at intermediate temperatures were investigated by using AC impedance analyzer,which shows a low area specific resistance (0.077 SIGMA cm2 at 1073 K and 0.672 SIGMA cm2 at 953 K).Moreover,the synthesis period of 20 h usually observed for conventional heating mode is reduced to a few minutes.Thus,the MWSG method is proved to be a novel,extremely facile,time-saving and energy-efficient route to synthesize LSCF powders.