POSITRON METHODS FOR THE STUDY OF DEFECTS IN BULK MATERIALS

The basic principles of positron annihilation physics are briefly disc ussed and the three most important experimental techniques used for bu lk studies are described (i.e. positron lifetime, angular correlation, Doppler broadening). Several examples of the use of the positron meth ods are discussed for metals, ceramics and molecular materials, which illustrate the sensitivity of the positron annihilation techniques to vacancy type defects. For example it is shown how information can be o btained about vacancy formation energies, vacancy migration and cluste ring, vacancy-impurity interactions, densities of rare gasses in bubbl es in metals, and about free volume in molecular materials.