“…After silver soldering to copper wire for electrical connection, each cathode was mounted in a cold setting resin. The samples were then ground, mechanically polished down to 1/4~ diamond paste, chemically polished using the solution of Gilpin and Worzala (12), and then etched to produce grain boundary grooves using the solution of Kilner and Plumtree (13). These silver cathodes were placed in a specially constructed cell, 2 cm deep by 3 cm in diameter, designed to fit u n d e r the objective lens of a Zeiss photomicroscope.…”