Abstract: Sr3YCo4-xMgxO10.5+δ(0≤x≤0.04) polycrystalline samples were prepared by solid state reaction method.The Mg doping effects on the crystal structure, electrical transport property and thermopower were studied.The results of crystal structure indicate that Sr3YCo4-xMgxO10.5+δ is tetragonal structure.Due to Mg2+(0.066 nm) partly substitude Co3+/4+(0.053 nm/0.061 nm), and the Mg doping enlarge the lattice parameters.The Seebeck coefficient measurement at 340~830 K shows that the thermopower decreases with increasing temperature, and Mg doping does not much affect the thermopower and carrier concentration.The resistivity measurement at 100~300 K shows that the resistivity decreases with increasing temperature and resistivity decreases with increasing Mg content.Scanning electron microscope results show that the number of pores decreases and grains connect closely.Combining the results of scanning electron microscope and thermopower indicate that the main effects of Mg doping impact on the electrical transport property are weaken the scattering of pores and grain boundaries, and improve the carrier mobility.The effects of carrier concentration is secondary.

Key words: Sr3YCo4-xMgxO10.5+δ(0≤x≤0.04) polycrystalline samples were prepared by solid state reaction method.The Mg doping effects on the crystal structure, electrical transport property and thermopower were studied.The results of crystal structure indicate that Sr3YCo4-xMgxO10.5+δ is tetragonal structure.Due to Mg2+(0.066 nm) partly substitude Co3+/4+(0.053 nm/0.061 nm), and the Mg doping enlarge the lattice parameters.The Seebeck coefficient measurement at 340~830 K shows that the thermopower decreases with increasing temperature, and Mg doping does not much affect the thermopower and carrier concentration.The resistivity measurement at 100~300 K shows that the resistivity decreases with increasing temperature and resistivity decreases with increasing Mg content.Scanning electron microscope results show that the number of pores decreases and grains connect closely.Combining the results of scanning electron microscope and thermopower indicate that the main effects of Mg doping impact on the electrical transport property are weaken the scattering of pores and grain boundaries, and improve the carrier mobility.The effects of carrier concentration is secondary.