Precursor Scavenging of Resistive Grain-Boundary Phase in 8 mol % Ytterbia-Stabilized Zirconia

Abstract

The grain-boundary conduction of 8 mol % ytterbia-stabilized zirconia (8YbSZ) was improved markedly by precursor scavenging via the two-stage sintering process. The most significant increase in the grain-boundary conductivity was found when the sample, whose conductivity was higher than that via Al 2 O 3 -derived scavenging, was heat-treated at 1250°C for ≥ 20 h. The formation of a stable Si-containing phase such as ZrSiO 4 during the first-stage heat-treatment was suggested as one probable scavenging route from the optimal heat-treatment temperature (HTT), long duration time ( > 20 h) at HTT, and the stability of the formed phase up to sintering temperatures (1500°C).