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The oxide doped Ce_ ( 0.9 ) of RE_ ( 0.1 ) O_ ( 2 -δ ) ( RE = Sm , Gd) ceramic material structure and electrical properties of

Author: NingDeZheng
Tutor: ZhouDeFeng
School: Changchun University of
Course: Organic Chemistry
Keywords: Solid electrolyte MgO Doping ZnO doped Scavenger Conductivity
CLC: TM911.4
Type: Master's thesis
Year: 2010
Downloads: 33
Quote: 0
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Abstract


The solid oxide fuel cell electrolyte is mainly oxidation of yttria stabilized zirconia (YSZ). Based on YSZ relatively limited oxygen ion conductivity, required operating temperature of up to 900 ° C. This not only increases the manufacturing cost, and accelerate the aging of the fuel cell system. Doped CeO2-based electrolyte with high ionic conductivity and low conductivity activation energy, is considered the most promising intermediate temperature solid oxide (IT-SOFC) electrolyte materials. CeO2 as a matrix, positive ions (such as Ca2, Sr2, Y3, La3, Nd3, Gd3 and Sm3) of different concentrations of doping can improve the electrical properties of the material. SiO2 is a ceramic material is one of the most common of the presence of basic impurities, even in high purity material is also difficult to discharge. Sintering SiO2 usually segregation to grain boundaries, blocking movement or diffusion of the grain boundaries, increasing the resistance of the grain boundary and reduce the conductivity of the electrolyte material of the polycrystalline. Therefore, add grain boundary impurity scavenger become the focus of research in recent years to reduce by the resistance of silicate film caused by grain boundary resistance, thereby increasing the conductivity of the grain boundary. Added CeO2-based solid electrolyte of Co2O3 impurity SiO2, Fe2O3 or Al2O3 able to better clear material to improve the conductivity of the grain boundary. Purity CeO2, the papers for the research system, artificially adding a certain amount of SiO2, and discuss the impact of the different oxides (MgO, ZnO) doped amount on the microstructure and the electrical properties of CeO2-based electrolytes, and the sintering temperature of the system , the scavenging effect of the grain boundary impurities. Focused on MgO, ZnO adding CeO2-based electrolyte materials grain boundary structure and electrical properties, and to determine the optimum amount of doping and the sintering temperature. (1) using the sol - gel synthesis of SiO2 content of 500 x 10-6 Ce0.9S00.1O2-δ powder (SDCSi), and 0-3.0 mol% MgO were added to SDCSi ceramic powders using X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) to characterize the material, electrochemical impedance spectroscopy (AC) electrical properties of the test material. The study shows that the doping of MgO make the SDCSi the lower sintering temperature of 100 to 200 ° C, to improve the density of the ceramic material; clear or reduce the harmful effects of the impurities at grain boundaries of ceramic material SiO2, significantly improved the grain / grain boundary conductivity and The total electricity rate; dual role of MgO doped with sintering aids and grain boundary impurity scavenger. (2) using the sol - gel synthesis Si02 content of 500 × 10-6 Ce0.9Gd0.1O2-δ powder (GDCSi), and 0-3.0 mol% ZnO were added to SDCSi ceramic powders with X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) to characterize the material, electrochemical impedance spectroscopy (AC) electrical properties of the test material. In the the ZnO doping amount range, the sintering temperature is decreased with the increase of the added amount, the small amount of ZnO doped can significantly increase the density of the sintered ceramics, the relative density reaches a maximum at a doping amount is 0.5 mol%, was also found ZnO doped can promote the growth of crystals. ZnO as a scavenger in 1400-1500 ℃ clear effect best, can significantly increase the grain boundary conductivity of the material.

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CLC: > Industrial Technology > Electrotechnical > Independent power supply technology (direct power) > Chemical power sources,batteries, fuel cells > Fuel cell
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