Journal of Inorganic Materials ›› 2014, Vol. 29 ›› Issue (9): 924-930.DOI: 10.15541/jim20140021

• Orginal Article • Previous Articles     Next Articles

Influence of NH4HCO3 on Microstructure of Ni/La10Si5.8Mg0.2O26.8 Anode

XIANG Li1, 2, DING Xiao-Fang1, 2   

  1. (1. Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, Ministry of Education; 2. School of Material Science and Engineering, Dalian University of Technology, Dalian 116024, China)
  • Received:2014-01-07 Revised:2014-03-28 Published:2014-09-17 Online:2014-08-21

Abstract:

Apatite-type lanthanum silicates are a new type of oxide-ion conductors. In the present research, nanosized apatite-type lanthanum silicate (La10Si5.8Mg0.2O26.8) powder was prepared through Sol-Gel method by using citric acid and nitrates. The nanosized lanthanum silicate powder was mixed with nanosized NiO powder according to weight ratio of 4:6, and with different amounts of NH4HCO3 as pore-forming agent. Porous composite anodes of Ni/La10Si5.8Mg0.2O26.8 were fabricated through sintering at 1400℃ and then reduced in H2 atmosphere at 600℃. Phases, surface morphology and porosity of the samples were characterized by XRD, FE-SEM and Archimedes method, respectively. Resistance of the anodes at room temperature was determined by ac impedance spectroscopy. The results show that the prepared Ni/ La10Si5.8Mg0.2O26.8 porous composite anodes are micro-crack free and the mean thermal expansion coefficient before reduction is 10.7×10-6 K-1. With increasing amount of pore-forming agent NH4HCO3, sizes of Ni grains, apatite-type silicate grains and pores decrease, but the porosity increases within the range of 30%-45%. The resistance of the anodes decreases at first and then increases as the amount of NH4HCO3 increases. Considering all these characteristics, including phases, surface morphology, porosity and resistance, the anode made with the pore-forming agent NH4HCO3 at ratio of 30wt% is the best.

Key words: Sol-Gel, apatite-type lanthanum silicate, anode, porosity, SOFCs

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