Table 3 Vibrational peaks identified in the BBBNDy glasses with assignments.

~ 450

Vibrations of Na²⁺, Ca²⁺ metal cations

^62,63

< 650

Vibrations of the Bi–O bond from BiO₆ octahedral and BiO₃ pyramidal structures

⁶⁴

~ 699 to ~ 702

Symmetric Bi–O stretching modes associated with BiO₃ pyramidal units, possibly superimposed with bending O₃B–O–BO₃ modes

^68,69,70

~ 709–751

Stretching B–O vibrations in borate tetrahedral units

⁷¹

~ 833–1059

stretching vibrations of B–O bonds in BO₄ tetrahedral units, with linkages of B–O–Bi structural units

^64,72

~ 1198 to 1295

Asymmetric B–O stretching vibrations in BO₃ units (ortho and pyro-borate configurations

⁷¹

~ 1312 to 1361

Asymmetric B–O stretching vibrations in BO₃ unit

⁷¹

~ 1397 to 1443

Vibrations of B–O stretching in BO₃ groups and Bi–O modes in BiO₆ and BiO₃ structures

^71,73