Structure and properties of off-stoichiometric Ba–Ga–Ge selenide glasses

Abstract

Off-stoichiometric glasses in the Ba-Ga-Ge-Se system with Se excess or deficiency (BGGS ± Se) are synthesized and their structure is characterized using Raman and multinuclear ( 77 Se, 71 Ga) magic-angle-spinning nuclear magnetic resonance (MAS NMR) spectroscopy. The results reveal that the structure of these off-stoichiometric BGGS ± Se glasses consists of a charge-compensated, partially covalent network of corner-sharing (Ga/Ge)Se 4 tetrahedra where [GaSe 4 ] − tetrahedra charge balance the Ba 2+ cations. Addition of excess Se to a stoichiometric BaSe-Ga 2 Se 3 -GeSe 2 glass with BaSe:Ga 2 Se 3 N 1 results in the formation of Se-Se linkages, while Se deficiency is accommodated via the formation of homopolar Ge-Ge bonds, in agreement with the continuously-alloyed structural scenario of purely covalent chalcogenide glasses. Such composition-dependent structural evolution is shown to be consistent with the corresponding variation in density and glass transition temperature.

Tunable ultra‐wideband NIR emission and irradiation resistance in novel Er3+/Tm3+/Pr3+ tri‐doped La2O3‐ Ga2O3‐Ta2O5 glasses synthesized using aerodynamic levitation method

“…According to the previous literature on 71 Ga MAS NMR measurement analysis of 4‐, 5‐ and 6‐coordinated gallium (Ga IV , Ga V , and Ga VI ) 27,28 . Therefore, the low‐frequency peaks at −27 and −4 ppm indicate the presence of six‐ and five‐coordinated gallium, respectively, while the broad distinct peak signals at 92 and 169 ppm are assigned to four‐coordinated Ga 29,30 . The above results verify that LGT matrix glass has 4–6‐ coordinated Ga, and gallium ions are mainly present as four‐fold coordination with a large fraction in the glass network.…”