POSITRON ANNIHILATION IN SOLID AND LIQUID Bi66.7Sn33.3 ALLOY

S. Chabik1, W. Rudzinska1, M. Szuszkiewicz2, C. Szymanski1

1 Institute of Physics, Opole University, Oleska 48, 45-052 Opole, Poland,
2 Institute of Experimental Physics, Wroclaw University, Maxa Borna 9, 50-204 Wroclaw, Poland

Peak coincidence counting rate, F(T), for Bi66.7Sn33.3 alloy in the temperature range from room temperature to 400ºC was measured. Hysteresis in the F(T) dependence in heating and cooling run was found. This results from the different contribution of positron trapping centers: microcrystals and grain boundaries near the solidus temperature. At the temperatures corresponding to the melting point for pure Sn and pure Bi significant changes of (T) parameter were observed. Liquid Bi66.7Sn33.3 alloy is homogeneous at temperatures above 300ºC.