Sintering of CuO investigated by positron lifetime spectroscopy

The sintering process of CuO under isochronal annealing has been investigated by positron lifetime spectroscopy. A long-lived component of 370±20 psec, observed in as-pressed samples and samples annealed atT⩽900 K, has been attributed to continuous channels along three-grain junctions. A short-lived component of about 224 psec is attributed to positron traps at two-grain interfaces. The annihilation parameters exhibit recovery stages which may be correlated with the stages of sintering. A drastic recovery, starting at 975 K, is correlated with the final stage of sintering. The results suggest a lifetime of approximately 147 psec for positrons in the bulk of CuO.