Microstructure degradation of an anode/electrolyte interface in SOFC studied by transmission electron microscopy

This work is one of the first attempts of using focused ion beam/lift-out (FIB/lift-out) techniques to prepare TEM specimens containing electrode/electrolyte interfaces in solid oxide fuel cells (SOFC). The present specimen was made from an Ni+YSZ (anode)/YSZ (electrolyte) half-cell which has undergone a long-term testing at a temperature of 850 degreesC over 1800 h in H-2 with 1% to 3% H2O under an anodic load of 300 mA cm(-2). The microstructure and phase chemistry in the interfacial region was analyzed using a JEM-3000F and EDS with a lateral resolution of nanometers. The impurity phase accumulated at the interface seen earlier by SEM have been characterized. It is a silicate glass with an amorphous structure and a composition of similar to90 mol% SiO2 as well as a few percent of Na2O,CaO, ZrO2, V2O3 etc. The silicate glass phase is distributed as films of nanoscale along the anode/electrolyte interface and Ni/YSZ grain boundaries. Its influence on the microstructural degradation of the interfacial region is evaluated. The FIB/lift-out techniques have been shown to be viable for specimen preparation from SOFC interface. (C) 2004 Elsevier B.V. All rights reserved.