SYNTHESIS AND CHARACTERIZATION OF La_(9.95)Ba_(0.05)Si_(5.8)Zn_(0.2)O_(26.775) CO-DOPED LANTHANUM SILICATE ELECTROLYTE FOR INTERMEDIATE TEMPERATURE SOLID OXIDE FUEL CELLS

摘要

Apatite-type lanthanum silicates have been successfully produced as the electrolyte materials for the intermediate temperature solid oxide fuel cells. In this paper, La_(9.95)Ba_(0.05)Si_(5.8)Zn_(0.2)O_(26.775) co-doped lanthanum silicate electrolyte has been prepared by the conventional solid-state reaction method to investigate the structural, morphological and electrical properties of the electrolyte. The oxyapatite electrolyte has been characterized by X-ray diffraction, scanning electron microscopy and electrochemical impedance spectroscopy. Hexagonal apatite structure of La_(9.95)Ba_(0.05)Si_(5.8)Zn_(0.2)O_(26.775) with space group P6_3/m formed as the major phase after sintered at 1600°C for 8 hours. Total oxide ion conductivity of La_(9.95)Ba_(0.05)Si_(5.8)Zn_(0.2)O_(26.775) ranges from 9.52 × 10~(-6) to 2.86 × 10~(-4)Scm~(-1) from 450 to 800°C, respectively.