Structural studies of Bi2O3-Nb2O5-TeO2 glasses

Abstract

Bi2O3-Nb2O5-TeO2 glasses show unusual annealing behavior with appearance of spherulites within the matrix glass structure for the Bi0.5Nb0.5Te3O8 composition. The textures resemble those found previously among polyamorphic Al2O3-Y2O3 glasses containing metastably co-existing high-and lowdensity phases produced during quenching. However the spherulites produced within the Bi2O3-Nb2O5-TeO2 glass are crystalline and can be identified as an "anti-glass" phase related to -Bi2Te4O11. We used high energy synchrotron X-ray diffraction data to study structures of binary and ternary glasses quenched from liquids within the Bi2O3-Nb2O5-TeO2 system. These reveal a glassy network based on interconnected TeO4 and TeO3 units that is related to TeO2 crystalline materials but with larger Te...Te separations due to the presence of TeO3 groups and non-bridging oxygens linked to modifier (Bi 3+ , Nb 5+ ) cations. Analysis of the viscosity-temperature relations indicates that the glassforming liquids are "fragile" and there no evidence for a LLPT occurring in the supercooled liquid. The glasses obtained by quenching likely correspond to a high-density amorphous (HDA) state. Subsequent annealing above Tg shows mainly evidence for crystallization of the "anti-glass" tellurite phase. However, some evidence may exist for simultaneous formation of nanoscale amorphous spherultites that could correspond to the LDA polyamorph. The quenching and annealing behavior of Bi2O3-Nb2O5-TeO2 supercooled liquids and glasses is compared with similar materials in the Al2O3-Y2O3 system.

Influence of Ho2O3 on Optimizing Nanostructured Ln2Te6O15Anti‐Glass Phases to Attain Transparent TeO2‐Based Glass‐Ceramics for Mid‐IR Photonic Applications

“…This implies that with the addition of Ho 2 O 3 in the TTLG network, binodal decomposition might have occurred in GCs . Moreover, the elemental maps presented in Figure S‐II(b) and (c), Supporting Information, can not reveal the compositional fluctuation in the phase‐separated domains of Ho 2 O 3 ‐substituted GCs, which confirms that the event of phase separation for relevant samples is governed by density fluctuation only . Furthermore, density fluctuation‐driven phase separation leads to the controlled crystallization via binodal decomposition.…”

“…The transparent GCs with the growth of nanostructured Bi 0.5 Nb 0.5 Te 3 O 8 (an analogous to the β ‐Bi 2 Te 4 O 11 fluorite‐type anti ‐glass phase) crystalline phase have been achieved owing to the controlled heat treatment of a 7.14Bi 2 O 3 −7.14Nb 2 O 5 −85.72TeO 2 glass system, which contains chains of corner linked TeO 3 and TeO 4 units with nonbridging oxygens (NBOs) coordinating NbO 6 and BiO 6 units . It could be understood that the presence of chains of corner linked TeO 3 and TeO 4 coordination polyhedral at an equal proportion and the presence of modifier cations surrounded by NBOs in the form of octahedral units lend the formation of tellurium‐rich anti ‐glass phase . Therefore, it is apparently clear that selecting more appropriate tellurium‐based glass composition and executing the controlled crystallization process support the development of nanostructured crystalline phases to obtain transparent GCs, which can further be utilized in nonlinear and NIR/mid‐IR (MIR) photonic applications.…”

Determining the Structure of Stable and Supercooled Liquids by High Energy X-Ray Diffraction

“…Although Pure TeO2 is known to be a poor glass former, glasses can be formed readily when small amounts of modifying components are added [18]. In a recent study the structure of glasses in the system Bi2O3-Nb2O5-TeO2, motivated in part by the similarity in the textures observed in some of these glasses with the apparent "polyamorphic" texture observed in yttrium aluminate systems [19].…”

Structure of bismuth tellurite and bismuth niobium tellurite glasses and Bi2Te4O11 anti-glass by high energy X-ray diffraction

“…The database of glass short-range structural properties such as cation-oxygen bond lengths, co-ordination numbers and bond angle distributions is required for the fundamental understanding of glassy materials, making structure-property correlations, for the mathematical modeling of glass density, elastic moduli, linear and non-linear refractive indices, stress-optical properties and for machine learning. [21][22][23][24] Wilding et al 25 studied the structure of binary and ternary tellurite glasses within the system: Bi 2 O 3 -Nb 2 O 5 -TeO 2 by high energy X-ray diffraction. These studies revealed a glassy network consisting of interconnected TeO 4 and TeO 3 units correlated to the crystalline TeO 2 materials but possessing larger Te/Te separations due to the presence of TeO 3 groups and non-bridging oxygens (NBOs) that are linked to modier (Bi 3+ , and Nb 5+ ) cations.…”