The Preparation And Performance Study Of Doping And Delafossite CuMO₂（M=Ga, Fe, Cr） And CuMO₂ /TiO₂

Transparent conductive oxide with good optical and electrical characteristics has been widely used in flat panel displays, solar cells, touching screen and other fields. Since 1997 Kawazoe et al. prepared delafossite CuAlO2 thin films, delafossite compounds have attracted increasing attention. This thesis reports the preparation of Sn- doping CuGaO2, and nanoplates CuFe O2 by hydrothermal method and CuCrO2/TiO2 complex structure by sol- gel method. The structure, morphology and optical properties of the samples were analyzed. The contents are divided into the followings:(1) CuGa1-xSnxO2(0 ≤ x ≤ 14.27 at.%) powders were synthesized by convenient hydrothermal method. The results revealed that the CuGa1-xSnxO2 powders were delafossite oxides with a rhombohedral(space group R- 3m) structure; the XPS spectra confirmed that the valence state of Sn was +4. CuGa1-xSnxO2 powders were paramagnetic at high temperature. The bandgap decreased from 3.83 eV to 3.45 eV with the concentration of doped Sn increasing. The offset of the X- ray diffraction pattern and the change in transmittance indicated that the critical threshold was reached when the Sn concentration reached 6.23 at.%.(2) Delafossite oxides CuFeO2 was prepared by hydrothermal method with glucose as a reducing agent. The SEM images show that CuFeO2 using 0.30 g glucose is hexagonal plate with well- defined edges, corners, and smooth surfaces at 200 °C for 48 h compared with others, and crystal size of CuFeO2 is about 3- 5 μm. The UV- visible absorption spectra indicates that there is a strong absorption of CuFeO2 in the visible range and the band gap is 1.74 eV. The oxidation reaction of the delafossite CuFeO2 starts at 450 °C in air and transforms to spinel phase.(3) CuCrO2/TiO2 complex structure was prepared by sol- gel method. The crystal structure and the optical properties were studied. The XRD result shows that CuCrO2/TiO2 complex structure is pure phase with no other impurity phases. CuCrO2 attaches to the surface of TiO2 in the form of small particles and CuCrO2/TiO2 forms a heterojunction structure from the TEM and HRTEM images. The UV- visible absorption spectra shows that there is a strong absorption of CuCrO2/TiO2 in the visible spectra and the direct optical band gaps of CuCrO2, TiO2 and CuCrO2/TiO2 are 1.78 eV, 3.01 e V and 1.92 eV, respectively.