The experimental and theoretical study of Al doped ZnSn(OH)6 to improve gas sensitivity

Abstract

The cubic ZnSn(OH)6 and Al@ZnSn(OH)6 were fabricated via hydrothermal method and detected by XRD, SEM, TEM, SAED, EDS and XPS technologies. XRD results show that the as-prepared sample is ZnSn(OH)6 and has good crystallinity. After doping Al, the lattice constant decreases and the (200) peak shifts to the right. SEM images display that the obtained samples are cubic lacking edges and corners, and have stepped stripes on the surface with a size of about 0.5–1 µm. XPS results reveal that the sample contained Zn, Sn and O. And O 1 s has three peaks of lattice oxygen, vacancy oxygen and chemisorption dissociated oxygen. The experimental results illustrate that the sensitivity of ZnSn(OH)6 to ethanol is obviously improved after doping Al element, and the optimal working temperature becomes lower. The resistance of ZnSn(OH)6 decreases to about 1/13 under 240 ℃. The molar ratio of Sn or Zn to NaOH will affect the crystal orientation and thus affect the morphology of ZnSn(OH)6. The calculation results show that the donor impurity level will be formed at the band bottom when Al doping ZnSn(OH)6. Which could further explain why the carrier concentration increases and the material resistance decreases after Al doping.