Electrical Conductivity of Y~(3+) Doped Ba(Ce,Zr)O_3 in Wet N_2 Atmosphere Prepared with the Addition of Brij-97

摘要

Y-doped barium cerate-zirconate (BCZY) ceramic oxide is proven to be a competent material as an electrolyte with high proton conductivity as well as chemical and mechanical stabilities in CO_2 and H_2O atmospheres. This ceramic oxide requires high processing temperature which will results in the increase of particle/grain size. Hence, modification on the synthesis route has been studied in reducing the particle/grain size of the ceramic by lowering the calcination temperature. In this work, BaCe_(0.54)Zr_(0.36)Y_(0.1)O_(2.95) (BCZY) powder was synthesized with addition of surfactant (Brij-97) through an established modified sol-gel route. Single BCZY perovskite phase was successfully obtained at calcination temperature of950°C which was lower than our previous study (T = 1100°C). The prepared sample was made into pellets by a dry pressing technique with diameter, d = 13 mm and thickness, t = 2 mm and then subjected to two-step sintering method prior to morphological and electrical measurements. Impedance measurement was carried out at intermediate temperatures (500 - 800°C) using Electrochemical Impedance Spectroscopy (EIS) in wet nitrogen atmosphere. Impedance spectrum was analysed to obtain the behaviour of grain core and grain boundary responses by a fitting procedure using brick-layer model. Scanning electron microscope (SEM) analysis of fractured pellet revealed that BCZY prepared with the assisted of Brij-97 exhibited dense, homogenous and less agglomerate grain with grain size around 88 nm, which may explain the enhancement in the total conductivity of the BCZY electrolyte from 7.54 × 10~(-4) to 2.24 × 10~(-3) Scm~(-1) at 650°C.