Positron annihilation in phase-separated and crystallized silicate glasses

Abstract

It is found that the amorphous phase separation has only minor effects on the annihilation characteristics. Only when glass starts to crystallize are the structural changes big enough to be clearly visible both in the positron lifetime spectrum and in the angular correlation curve of the 2 gamma annihilation radiation. Intensities of the longer lifetime components decrease and the angular correlation curves broaden markedly. These effects can be utilized to follow the progress of crystallization and some results on a lithium silicate glass are presented.