Synthesis and Thermal Characterization of Co-doped ZnO Nanocomposites Prepared by Sol-gel Method

摘要

Polyparaphenylene/Zn_(0.925)Co_(0.075)O(PPP/Zn_(0.925)Co_(0.07)5O) nanocomposites were synthesized by using a sol-gel method and their thermal conductivity properties were measured. The XRD pattern of Zn_(0.925)Co_(0.075)O shows the single phase wurtzite structure. The SEM images show that the lighter-contrast area is PPP and the dark-contrast area is the polycrystalline of Zn_(0.925)Co_(0.075)O. The increase in the band edge is a clear indication for the incorporation of Co inside the ZnO lattice. The observation of three additional absorption peaks provided evidence that the 3d~7 high-spin configuration of Co~(2＋) under the tetrahedral crystal field was probably formed by neighboring O~(2-) ions. With the increase of the PPP content, the thermal conductivity of nanocomposite samples is smaller than those of pure Zn_(0.925)Co_(0.075)O. Due to the high density of interfaces and grain boundaries present in the nanocomposites, the scattering of phonon across a broad wavelength spectrum was enhanced. This suppressed the lattice thermal conductivity of the nanocomposites significantly.