Super-fast response humidity sensor based on La0.7Sr0.3MnO3 nanocrystals prepared by PVP-assisted sol-gel method

La0.7Sr0.3MnO3 (LSMO) nanocrystals were prepared by polyvinylpyrrolidone (PVP)-assisted sol-gel method and characterized by a variety of characterization techniques. The humidity sensor based on LSMO nanocrystals was fabricated and its humidity sensing properties were investigated at room temperature (25 degrees C) within the relative humidity (RH) range of 11-95%. The optimum working frequency of the LSMO humidity sensor was 10 Hz and the impedance variation was about four orders of magnitude within the whole humidity range from 11% to 95% RH. The LSMO humidity sensor was of super-fast response speed, which was only about 0.8 s from 11% to 95% RH at 10 Hz. The super-fast response property may be ascribed to the strong hydrophilicity of LSMO nanocrystals. In addition, the LSMO humidity sensor was of good reproducibility, stability, small humidity hysteresis (4% RH at 75% RH) and a fast recovery speed (similar to 4.9 s). These results indicate the LSMO nanocrystals can be used as a novel humidity sensing material to fabricate high performances humidity sensors. (c) 2017 Elsevier B.V. All rights reserved.