Table 2 Assignments of the main vibrational modes for the BGB-xTb glasses.

1 and 2

220 and 305

Bending modes of Ge–O in the glassy network

^31,32

3

340–411

Vibration of Ge–O⁻ (NBO) corresponding to the Q¹ species

³²

4

470

Vibrations of Ge–O–Ge bonds in 3-membered GeO₄ rings

³⁵

5

520

Symmetrical vibrations of Ge–O–Ge bonds

^34,35

6

574–598

Ge–O–Ge bending mode

²⁵

7

752

Symmetrical stretching vibrations of metaborate chains

^35,36

8

740–777

Vibrations of borate rings (di-triborate rings)

³⁵

9

810–820

Symmetrical stretching vibrations of Ge–O⁻ (NBO) in Q² species

^35,37

10

790–860

Symmetrical stretching vibrations of Ge–O⁻ (NBO) in Q³ species

^35,37

11

907–930

Vibrational mode of diborate groups

³⁵

12

1200

Diborates

³⁵

13

1337

BO_3/2

³⁵

14

1427

BO_3/2ring

³⁵

15

1495

B–O⁻

³⁵