Study On The Preparation And Electrochemical Properties Of BaCeO₃-based Proton Conductor

Perovskite-type proton conductors had a wide range of applications in hydrogen sensors,fuel cells,catalytic synthesis,etc.In this work,a series of proton conductors based BaCeO3 with Y doped and Ba defect were synthesized by the sol-gel auto combustion method,and then the influence of Y proportion doped,Ba proportion defect and sintering temperature on the conductivity and conductivity activation energy of the proton conductors was studied.It was also focused on the correlation between the conductivity and conductivity activation energy of the proton conductors and the influence factors to obtain the optimum composition ratio of the element and the sintering temperature.In this paper,a series of BaCe1-xYxO3-?(x=0,0.05,0.10,0.15,0.20)and BayCe0.8Y0.2O3-?(y=0.85 0.90,0.95,1)proton conductor precursor powders were synthesized by sol-gel auto combustion method,whose complexing agents were citric acid and EDTA.The precursor was sintered at 1000? under the static pressure,and then the proton conductor ceramic material was prepared by sintering at 1500 ?,1550?,1600? and 1650?.XRD results indicated that the precursor powder calcined for 6h at 1000? had been basically formed perovskite phase,while a few miscellaneous peaks still existed.Powders calcined by sintering 1500? for 4h had formed a single perovskite phase,due to a small amount of Ba volatilizes,while a small amount of CeO2 phase existed when the sintering temperature increased to 1650??Under the standard hydrogen atmosphere(0.49%hydrogen),we tested the resistance of BaCe1-xO3-?(x=0,0.05,0.10,0.15,0.20)and BaCe0.8Y0.2O3_?(y=0.85,0.90,0.95,1)proton conductor with temperature range from 800 to 1000?by the alternating current impedance spectroscopy method,and then obtained the conductivity and the conductivity activation energy by formula to find their values change with the amount of Y doping,loss of Ba and the sintering temperature.Experimental results showed that the conductivity of Y-doped cerium acid barium proton conductor increased with the amount of Y-doped and decreased with the amount of Ba defected,while for the conductivity activation energy,the result was opposite.At the same test temperature and atmosphere,the conductivity of BaCe1-xYxO3-? perovskite proton conductor increased with the increase of Y quantity at B-site.When the testing temperature ranged from 800?to 1200? x=0.20,we could get the maximum conductivity and the minimum conductivity activation energy which was 6.39 ×10-2 S·cm-1 and 0.494 eV,respectively.For the BayCe0.8Y0.2O3-?,proton conductor(y=0.85?0.90?0.95.1),with the increases of the amount of Ba deficient the conductivity reduced from 6.39×10-2 S· cm-1 to 2.91 ×10-2 S·cm-1,and the conductivity activation energy increases from 0.494eV to 0.668eV.Meanwhile,for the Y-doped cerium acid barium proton conductor,the experimental results showed that sintering temperature was the important factors of conductivity and conductivity activation,increasing the sintering temperature appropriately could increase the conductivity and lower the conductance activation energy,but when the temperature was higher than the 1550?,increasing the sintering temperature would decrease the conductivity and increased conductance activation energy.