Positron lifetime measurements of vacancy defects in complex oxides

Abstract

Native defects in complex oxides play a crucial role in determining their optical, electrical, and magnetic properties and it is difficult to identify and characterize them. Positron lifetime spectroscopy is a powerful technique to study vacancy defects; however its application to complex oxides has been limited. In this work we apply positron lifetime spectroscopy to study open volume defects in rare earth doped yttrium aluminum garnet (YAG) complex oxides grown in argon atmosphere. In YAG single crystals, positron lifetime measurements identified isolated aluminum vacancies and complexes of aluminum vacancy and neighbor oxygen vacancies. Thermoluminescence measurements were also performed to elucidate the interaction between trapping defects and luminescence centers. By combining positron lifetime and thermoluminescence, both the defect type and its effect on the optical properties of YAG crystals were revealed.