Preparation of yttria stabilized zirconia membranes on porous substrates by a dip-coating process

Gas-tight yttria stabilized zirconia (YSZ, 8 mol.% Y2O3) membranes with expected composition were coated on porous ceramic substrates by a dip-coating process with YSZ sol, which was prepared by ultrasonic dispersion of YSZ powder in ethanol. The YSZ powder was synthesized by co-precipitation from inorganic aqueous solutions, followed by azeotropic distillation and sintering at 600°C for 2 h. The crystalline structure of YSZ powder was characterized by X-ray diffraction. Microstructures of YSZ membranes were analyzed by scanning electron microscopy and nitrogen permeation testing. The investigation showed that defects in the membranes could be gradually removed by repeating the dip-coating procedures. The electrical transport properties of the YSZ membrane were analyzed by AC impedance spectroscopy. The electrical conductivity of the membrane was 0.001 s cm−1 at 900°C and the activation energy of electrical conductivity was found to be 87.5 kJ mol−1.