X-ray absorption spectroscopy for the study of glasses and glass-ceramics for optical applications: A comprehensive review

X-ray Absorption Spectroscopy (XAS) is an essential technique for the elucidation of local atomic structure and oxidation state in glasses and glass-ceramics of optical interest. XAS gives element-selective information on disordered materials unlike conventional diffraction techniques, so one can discuss dopant environments, short- and medium-range order, and mechanisms of crystallization. The review provides a general survey of XAS applications on different glass families for optical applications, including silicates, borates, borosilicates, phosphates, heavy metal oxides, fluorides, chalcogenides, oxyfluorides and glass-ceramics. Principal emphasis is put on structural role of rare-earth, transition, and post-transition metal ions whose coordination environment and oxidation state play a crucial role in determining photoluminescence, quantum yield, and nonlinear optical properties. The review also addresses methodological issues in XAS data acquisition and analysis, e.g., detection modes, spectral fits, and application of complementary computational packages. With optical functionalities correlated with structural parameters, this review highlights the role of XAS in rational photonic material design.