Luminescent P2O5-MoO3-Bi2O3-K2O Glasses and Glass Ceramics on their Basis: Insights from Experimental and Computational Studies

This paper presents results of complimentary experimental (by electron microscopy, X-ray diffraction, diffuse reflectance, photoluminescence (PL) and FTIR spectroscopy) and computational (by molecular dynamics and DFT-based electronic structure methods) studies of oxide glasses of xP2O5-yMoO3-zBi2O3-(1-x-y-z)K2O system and glass ceramics based on them (crystal @glass), where the KBi(MoO4)2 complex oxide is the crystal component (KBi(MoO4)2 @glass). The behavior of the observed PL characteristics is analyzed in synergy with results of calculations of their atomic structures and changes in the oxygen environment of bismuth atoms during the transition crystal interphase glass. It has been shown that the optical absorption and PL characteristics of such systems are largely determined by content of Bi2O3 and MoO3 oxides in the initial charge, and by content bismuth ions in different charge states which exist in the produced glass and glass ceramics. It was found that the blue PL (spectral range 375 – 550 nm) of both glasses and glass ceramics originates from radiative transitions 3P1 1S0 in bismuth ions Bi3+. The yellow-red PL (range 550 – 850 nm) should be mainly associated with the luminescence of bismuth ions in lower charge states, Bi2+, Bi+ and Bi0. The thickness of the interphase layers of glass ceramics is estimated to be 1.5-2.0 nm. It has been shown that the changes in the spectra of optical absorption and PL / PL excitation of the glass ceramics occur due to the decrease in the number of oxygen atoms in the nearest surrounding of bismuth ions in the interphase region and these changes can be used for spectral probing of the formation and presence of interphase layers.