Effect of Composition and Morphology on Sensor Properties of Aerosol Deposited Nanostructured ZnO+In 2 O 3 Films

Abstract

The structural characteristics are investigated of nanoheterogeneous films comprising ZnO, In2O3 and ZnO + In2O3 composite produced by aerosol spray pyrolysis technique (SPT). The process uti-lizes water solutions of zinc chloride and indium nitrate precursors. The X-ray diffraction data show that the SPT process results in polycrystalline films of hexagonal wurtzite type ZnO, and In2O3 crystals of cubic structure. SPT-synthesized ZnO + In2O3composites contain mixtures of these crystals. The morphology of the synthesized films is studied by scanning electron microscopy as well as the dependence of morphology on the synthesis conditions, specifically the temperature of the aerosol precipitation and the concentration of the precursors in solutions. The characteristics of nucleation and growth of oxide crystals during the synthesis of ZnO + In2O3 composite films are also considered. The film with the composition 25 wt% ZnO + 75 wt% In2O3 contains a large num-ber of small crystal aggregates of arbitrary shape with a high density of contacts between the ag-gregates and are characterized by a homogeneous structure with high dispersion. Such mor-phology has high specific surface, which favors high sensory response. In addition, in this range of aggregate composition the relationship between the particles of the catalytically active compo-nent-ZnO, cleavage of hydrogen molecule, and In2O3particles with a high concentration of conduc-tion electrons is close to optimal for the maximum sensory effect in the detection of hydrogen.