Influence of Doping on Structure and H2 Sensitivity of Nano-SnO2
In order to improve the gas sensitivity of SnO2, Ni-doped and Co-doped nano-powders were prepared by the homogenous co-precipitation method using analytical pure SnCl4•5H2O and NH3•H2O as main materials under different doped ratios n (M2+)/n (Sn4+). The gas sensors were made by the thick film technique on mica substrates. The structure and crystal properties of the samples were investigated by X-ray diffraction (XRD). The results indicated that Sn4+ in the crystal lattice of SnO2 was partly replaced by M2+, which resulted in the change of the M-O bond lengths and the lattice parameters. The sensitivities of the sensors in H2 atmosphere with different concentrations at 75°C were tested. As a result, doped M2+ especially Ni2+ improves its H2 sensitivity, the sensitivities increases linearly with the increasing H2 concentration, and the best doping n(M2+)/n(Sn4+) of preparing gas-sensing material were obtained. The results show that doping which leads to the asymmetry of electrovalent balance of M-O octahedrons improves the activities and semiconductor properties of the powders. These studies play an important part in detecting reductive gases in special environment.
Jinsheng Liang and Lijuan Wang
H. F. Liu et al., "Influence of Doping on Structure and H2 Sensitivity of Nano-SnO2", Advanced Materials Research, Vol. 96, pp. 105-110, 2010