Preparation And Study On The Electrical Property Of Two Kinds Of Perovskite Structure Of Mixed Conductor Materials

The perovskite structure of mixed conductor materials have a wide range of technical application in fuel cells, sensors and oxygen separation and so on. It is of great significance to study on the perovskite structure of mixed conductor materials, in order to realize the21st century’s sustainable development program in our country. The structures, electrical properties and charge carrier types of the perovskite structures of YBaA2O5+(A=Co,Fe) and LaSr3Fe3-xMnxO10-mixed conductor materials were studied in this paper.The YBaA2O5+δ(A=Co, Fe) and LaSr3Fe3-xMnxO10-(x=0.1,0.2,0.4,0.6,0.8,1.0) powder were prepared by the sol-gel, its structure and thermal stability were determined and analysised by X-ray diffraction and thermal gravimetric.At different quenching temperature, the average valence of valence ions (Co, Fe and Fe/Mn) and oxygen non-stoichiometric in two kinds of mixed conductor were measured by iodine titration. The influence of quenching temperature on the average valence of ions and the oxygen non-stoichiometric were discussed. Found:at different quenching temperature, the average valence of Co and oxygen non-stoichiometric increased when the quenching temperature rised at the beginning, the average valence of Co and oxygen non-stoichiometric were the maximum at300℃, then gradually decreased. The average valence of Fe and oxygen non-stoichiometric reduced when the quenching temperature rised. The average valence of Fe/Mn reduced when the quenching temperature rised; and the oxygen non-stoichiometric increased when the quenching temperature rised, and got their defect equations.By seebeck coefficient measurements, showed that the YBaA2O5+δ(A=Co, Fe) and LaSr3Fe3-xMnxO10-mixed conductor materials were p-type conductor in certain temperature range.By using four-terminal method, the YBaA2O5+δ(A=Co, Fe) and LaSr3Fe3-xMnxO10-mixed conductor conductivity were studied. In the range200℃to325℃, the conductivity of sample increased with temperature in YBaCo2O5+δ mixed conductor, which showed semiconducting property. The conductivity of the sample decreased when the temperature was higher than325℃, which showed metallic conductive property. At different temperature, the conductivity decreased with temperature in YBaFe2O5+δ mixed conductor. In LaSr3Fe3-xMnxO10-mixed conductor, the conductivity of Mn-doped samples appeared the semiconductor-metal transition, the conductivity of the sample was the maximum when the Mn-doped was x=0.1, and the conductivity of the sample was the minimum when the Mn-doped was x=1.0. Under the same Mn-doped, the conductivity of the LaSr3Fe3-xMnxO10-samples decreased with temperature.Finally, the scaning Kelvin probe was used for the first time to test the superficial potential of the YBaA2O5+δ mixed conductor sample at the different quenching temperature and LaSr3Fe3-xMnxO10-mixed conductor sample with different Mn-doped quantity. Qualitative analysised of sample surface electron was stimulated energy required.