Preparation And Thermoelectric Properties Of SrCuO₂

Layered oxides with3d transition group metallic element have drawn much attention for their remarkable thermoelectric power and lower resistivity. The orthorhombic SrCuOi also have the similar layer structure that the double CuO chains and the Sr-O layer alternately stack along the b-axis. The CuO chains were responsible for electrical conductivity, while the Sr-O layers acted as charge reservoir. In this thesis, the preparation and the thermoelectric performance of orthorhombic SrCuO2over the temperature range between373K and873K were investigated.The solid state reaction method was investigated and improved to prepare single phase SrCuO2and the Ni doped samples. Used the improved solid state reaction method, a series of Ni doped, K, Na doped and co-doped SrCuO2samples were prepared.The effect on the structure of orthorhombic SrCuO2by element doped was investigated that the doping elements have entered into the lattice in a certain degree and caused changes in lattice. The critical doping amount of Ni was discussed combining with the XRD patterns, the SEM images, the variation of lattice parameters and the variation of unit cell volume of Ni doped SrCuO2samples. The reason for the disappearance and generation of the impurity phases in co-doped samples was discussed according to the change rules of the variation of lattice parameters caused by Ni doped and K, Na doped, respectively. In addition, resulted from the SEM images of co-doped SrCuO2samples, the effect of increase on grain size of samples caused by K, Na doped would be suppressed by Ni doped.The thermoelectric performance in orthorhombic SrCuO2and the effect on thermoelectric performance by element doped were investigated. Resulted from thermoelectric measurements, the samples exhibited Seebeck effect over the temperature range between373K and873K. The major carriers in all samples were holes for their positive Seebeck coefficient. The results showed that the Seebeck coefficient and electrical conductivity were increased by Ni doped and K, Na doped, respectively. The thermoelectric performance for SrCuO2was enhanced by appropriate doping amount of Ni and/or K, Na.