Influence of Zn-substitution on structural, morphological, electrical, and gas sensing properties of Zn Al2O4 (x = 0.1 to 0.5) synthesized by a sol-gel auto-combustion method

Abstract The nanosphere decorated needle-like morphology of zinc-substituted aluminate having general formula ZnxAl2O4 (x = 0.1, 0.2, 0.3, 0.4, and 0.5) (ZAN) samples were synthesized by a sol-gel auto-combustion method. The phase formation and stability temperature were confirmed by TG-DTA analysis. XRD study confirmed the formation of a cubic spinel structure of ZAN samples. The effect of Zn-substitution on structural and morphological properties of aluminate were investigated using X-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), Transmission electron microscopy (TEM), Field emission scanning electron microscopy (FESEM), and Energy dispersive X-ray analysis (EDAX). The D.C. electrical resistivity study of ZAN samples revealed that resistance decreased with increasing temperature confirmed semiconducting nature. Nanosphere existing on micro-needles of zinc-substituted aluminate gas sensor revealed sensing to several analyte gases such as H2S, Cl2, CH3OH, SO2, and NO2 working at room temperature to 300 °C. The Zn0.4Al2O4 compositional gas sensor produced the highest response at operating temperature 200 °C to 100 ppm H2S. The results revealed that the prepared nanosphere decorated needles of the ZAN sensor was sensitive and selective to H2S gas.