Humidity sensing behavior of Cr-PET (polyester) fiber-doped ZnO nanostructures

In the present study, the humidity sensing character of zinc oxide (ZnO) doped with chromium (Cr): polyester (PET) fibers (ZCPET0, ZCPET1, ZCPET2, ZCPET3, and ZCPET4) samples have been investigated. PET fibers having hydrophobic nature, low cost and low moisture regain (0.42%) and have been used in conjunction with ZnO and Cr. It was observed that sensing mechanism strongly depends on sintering temperature, composition and crystallite size. Humidity gas sensing parameters were also studied. The synthesized pellets were characterized using X-ray diffraction, scanning electron microscopy (SEM) and humidity gas sensor. The crystallite sizes of samples ZCPET0, ZCPET1, ZCPET2, ZCPET3 and ZC4were estimated using the Debye–Scherer equation and found to be 37.0, 40.8, 43.6, 62.0 and 65.8 nm, respectively. The crystallite size increased with increased Cr-PET doping concentration. The SEM analysis exhibited rod-shaped nanostructure of Cr-PET-doped ZnO pellets annealed at 600 °C. The value of sensitivity was found in the range of 12.9 MΩ/%RH-20.5 MΩ/%RH. Humidity gas sensing characteristics revealed low hysteresis, smaller amount of aging effect and high reproducibility by varying wt.% of Cr-PET-doped ZnO samples.