EFFECT OF HEAT TREATMENT ON POSITRON ANNIHILATION OF GLASSY Bi_(1.6)Pb_(0.4)Sr_(1.9)Ca_2Cu_(3.1)O_y

Effects of isochronal annealing on the positron annihilation of glassy Bi_(1.6) Pb_(0.4) Sr_(1.9)Ca_2 Cu_(3.1)O_y(BPSCCO)have been reported.It is shown that the crystallization influences obviously the positron annihilation characteristics of BPSCCO.A maximum is found in the region of crystallization temperature in curves of mean lifetime and peak/wing ratio, one of Doppler Iineshape parameter,with annealing temperature;the bulk lifetime of positron annihilation in the glassy state is longer than that in the crystalline one.Positron annihilation spectroscopy could be used for studying structure of glassy BPSCCO and its change with heat treatment.