Photoluminescence of Sn^2+-centre as probe of transient state of supercooled liquid

Physical properties of oxide glasses depend on the cooling process from the super-cooled liquid state. It is demonstrated that the Sn2+ species possessing electrons in the outermost shell can function as a qualitative probe cation to evaluate the randomness of the host glass network. With slower cooling, the formation of a more dense glass network is observed as confirmed by the heat capacity, elastic modulus, 11B NMR, first sharp diffraction peak of X-ray diffraction, and Boson peak results. The optical absorption, photoluminescence (PL), and Sn K-edge X-ray absorption fine structure data strongly suggest that the aggregation of Sn2+ results from the slow-cooling of the melt, and that PL properties of Sn2+ can be affected by the ordering of the transient state of super-cooled liquid. The results highlight that the structure of the transient state of glass is important for the functionalization of optical glasses.