Self-Healing Semiconducting Chalcogenide Glasses Upon Gamma Irradiation

We present a combined theoretical-experimental approach to the quantitative processing-structure-property relationship correlating the time-dependent structural and optical responses of chalcogenide semiconducting Ge-Sb-S bulk glasses to their metastable topological coordination defects. These defects are characterized by an irradiation-induced increase in the concentration of edge-shared GeS_4/2 tetrahedra bonding units, which gradually decreases to a pre-irradiation level during recovery, thus illustrating the glass’ metastable behavior. This time-dependent structural change gives rise to the evolution of the glass’s mass density that correspondingly induces a change and subsequent relaxation of linear refractive index and bandgap energy. The novelty of our study is that multi-faceted aspects of such a key infrared chalcogenide glass, including optical, electronic, morphological, chemical, and microstructural properties, were monitored and cross-correlated as a function of time following gamma irradiation to identify origins behind the material system’s behavior with such exposure as compared to base unirradiated material. This is, to our knowledge, the first-ever integrated approach (summarizing pre- and post-exposure properties on the same samples) to the phenomenon. Our findings may shed light on the lingering question on the microscopic origin behind the self-healing process in chalcogenide glasses. The behavior in metastable bulk chalcogenide glasses serves as a key cornerstone that will enable the material system to be deployed as robust, reversible radiation sensors in extreme environments such as space and ground-based radioactive facilities where gamma ray is characteristically abundant.