Structural role of Nb2O5 in glass-forming ability, electronic polarizability and nanocrystallization in glasses: A review

Structure-Property Correlation in Sodium Borophosphate Glasses Modified with Niobium Oxide

“…This compound, according to the previous structural studies [25,26], contains niobium atoms in NbO 6 octahedra. In the structure of α−NbOPO 4 , these octahedra form chains with Nb-O-Nb linkages and also cross-connections with PO 4 tetrahedra and Nb-O-P linkages [17,27]. Crystallization processes usually change only medium-range order present in the glasses, but not shortrange order structural motifs.…”

Nanoscale composition fluctuations and crystallization process: Case study in Li2O–SiO2‐based glasses

“…Recently, the present authors’ group analyzed and discussed the structural role of Nb 2 O 5 in glass forming ability, electronic polarizability, and nanocrystallization 39 . The structural features in RNS glasses are summarized as follows 39 : (1) Nb 5+ ions are present as the octahedral coordination state of NbO 6 , (2) NbO 6 octahedra are distorted intrinsically due to the second‐order Jahn–Teller effect, and two kinds of distorted NbO 6 octahedra are basically present, that is, slightly and highly distorted NbO 6 octahedra, (3) linkages of Nb–O–Si bonds are created between NbO 6 octahedra and SiO 4 tetrahedra, (4) clustering of slightly distorted NbO 6 octahedra is formed, (5) R + ions can act a role not only as modifiers for SiO 4 tetrahedra, that is, the formation of NBOs (Figure 5A), but also as charge compensators for negative NbO 6 octahedra (Figure 5C). Considering these structural features, our research group 39 proposed the DNCF model for Li 2 O–Nb 2 O 5 –SiO 2 glasses with high Nb 2 O 5 contents, and its model is shown in Figure 8 schematically.…”

“…The structural features in RNS glasses are summarized as follows 39 : (1) Nb 5+ ions are present as the octahedral coordination state of NbO 6 , (2) NbO 6 octahedra are distorted intrinsically due to the second‐order Jahn–Teller effect, and two kinds of distorted NbO 6 octahedra are basically present, that is, slightly and highly distorted NbO 6 octahedra, (3) linkages of Nb–O–Si bonds are created between NbO 6 octahedra and SiO 4 tetrahedra, (4) clustering of slightly distorted NbO 6 octahedra is formed, (5) R + ions can act a role not only as modifiers for SiO 4 tetrahedra, that is, the formation of NBOs (Figure 5A), but also as charge compensators for negative NbO 6 octahedra (Figure 5C). Considering these structural features, our research group 39 proposed the DNCF model for Li 2 O–Nb 2 O 5 –SiO 2 glasses with high Nb 2 O 5 contents, and its model is shown in Figure 8 schematically. As described in Section 1, in this model, the structure of LNS glasses consists of Li 2 O–Nb 2 O 5 ‐rich (small SiO 2 contents) and Li 2 O–SiO 2 ‐rich (large SiO 2 contents) regions, and the nucleation and crystal growth of LiNbO 3 take place predominantly in the Li 2 O–Nb 2 O 5 ‐rich region being more fragile compared with the Li 2 O–SiO 2 ‐rich region.…”

“…We focus mainly on lithium disilicate Li 2 O-2SiO 2based glasses and Li 2 O-Al 2 O 3 /Ga 2 O 3 /Nb 2 O 5 -SiO 2 glasses that are precursor glasses for glass-ceramics with excellent practical performances and potentials such as thermal, mechanical, and optical properties. 37 The oxides of Al 2 O 3 , Ga 2 O 3 , and Nb 2 O 5 have been considered to be intermediates, 38,39 and thus, ternary Li…”

“…We focus mainly on lithium disilicate Li 2 O–2SiO 2 ‐based glasses and Li 2 O–Al 2 O 3 /Ga 2 O 3 /Nb 2 O 5 –SiO 2 glasses that are precursor glasses for glass–ceramics with excellent practical performances and potentials such as thermal, mechanical, and optical properties 37 . The oxides of Al 2 O 3 , Ga 2 O 3 , and Nb 2 O 5 have been considered to be intermediates, 38,39 and thus, ternary Li 2 O (modifier)–Al 2 O 3 /Ga 2 O 3 /Nb 2 O 5 (intermediate)–SiO 2 (glass former) glasses are also good examples for the discussion of nanoscale composition fluctuations. We also compare the performance of Li 2 O–SiO 2 ‐based glasses with Na 2 O/K 2 O–SiO 2 ‐based glasses to draw the role and features of Li 2 O in nanoscale composition fluctuations in multicomponent oxide glasses.…”