Investigation of the structural and electrical properties of nanocrystalline YSZ for SOFC application

Abstract

Nanocrystalline yttria-stabilized zirconia (YSZ) was synthesized by a modified co-precipitation method. The process involves the use of molecular water associated with metal precursors to facilitate the hydroxylation. In this method, triethylamine was used to generate hydroxide ions from the molecular water of precursors, which helps to produce the metal hydroxides. Since no external water is utilized during the precipitation process, it is expected that the as-prepared and calcined materials should have minimum aggregation caused by the hydrogen bonding. The as-prepared and calcined YSZ powders are characterized by X-ray powder diffraction (XRD), energy dispersive X-ray analysis (EDX), Brunauer Emmett-Teller (BET), transmission and scanning electron microscopy (TEM and SEM) and electrochemical impedance spectroscopy (EIS). Cubic phase YSZ, having yttria content of 8 mol%, has been formed at a calcination temperature of 650°C. The YSZ powder has a surface area of 88 m² g^–1 and the particle diameters measured from TEM are in the range of 8–15 nm, which is in good agreement with the average particle diameter, which is ~12 nm, obtained from surface area. The materials produced have grain boundary oxygen ion conductivity of 0.073 S cm^–1 at 800°C, which is one of the main parameters for SOFC to get higher power density.