Synthesis and characterization of nanocrystalline ZnWO4-ZnO composites and their humidity sensing performance

Abstract

We investigate the experimental results on the composites ZnWO4-ZnO for electrical and humidity sensing properties are described. ZnWO4 (ZW) prepared by precipitation method and this prepared zinc tungstate mixed with ZnO (ZO) in different mole rations (100:0, 80:20, 60:40, 40:60, 20:80, 0:100). The products were characterized in detail by multi techniques: X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), Brunauer-Emmett-Teller (BET) analysis and vibrating sample magnetometer (VSM). The composites were sintered in the form of the disc and subjected to dc resistance measurements. The dc resistance of these composites decreased on exposure to humidity at room temperature. These results demonstrate composite ZWZO-46 has the highest humidity sensitivity Sf = 3416, with a response and recovery time of 50 s and 100 s respectively. Keywords: Composites, Relative humidity, Humidity sensor, VSM, Hysteresis