Synthesis, Characterization and Humidity Sensitive Properties of Nanocrystalline LaCoxFe1–xO3

The nanocrystalline LaCoxFe1–xO3 with different concentrations of Co was prepared by polyethylene glycol (PEG) sol-gel method and characterized by differential thermal analysis and thermal gravimetric analysis (DTA-TGA), X-ray diffraction (XRD), and scanning electron microscope (SEM). It was found that the crystal structure of perovskite-type could be obtained at 600 °C, and the concentration of Co had significant effects on the solid-state reaction and the average particle size of the obtained nanocrystals. Furthermore, the humidity-sensitive properties of nanocrystalline LaCoxFe1–xO3 were investigated, and it was found that LaCo0.3Fe0.7O3 exhibited higher sensitivity to humidity compared with other samples. The addition of Na2CO3 improved the humidity-sensitive properties of this sample, and made its response to humidity good in the whole humidity range of 11%–95% relative humidity (RH).