Effect of Bi₂O₃ on physical, optical and structural properties of mixed oxide glass system Na₂B₄O₇-(15+2x)Bi₂O₃–(24-x)GeO₂ –CuO

The effect of bismuth oxide (Bi₂O₃) and germanium oxide (GeO₂) substitution on the physical, optical, and Fourier transform infrared (FTIR) properties of CuO-doped (60-x)Na₂B₄O₇–(15+2x)Bi₂O₃–(24-x)GeO₂ –1CuO (NBGC) glass system was reported. The NBGC glasses were prepared by a melting and quenching process. Various physical, optical parameters like, molar electronic polarizability (α
m
), theoretical density (ρ
th
), molar refraction and metallization criterion (M
c
), molar volume (V
M
), oxidation polarizability (α
o
2-
), Urbach energy(∆E), refractive index (n), theoretical basicity (˄
th
), experimental basicity (˄
exp
), Energy gap (E
opt
), and theoretical interaction parameter (A
th
) were estimated. Density and molar volume trends exhibited a characteristic non-monotonic behavior, revealing boron anomaly. The refractive index and optical energy gap (E
opt
) exhibited a non-monotonic variation corresponding to the observed structural changes. The experimental basicity values varied from 0.74 to 0.95 and were in good agreement with theoretical values. Molar refraction and molar polarizability values have shown an upward trend. Higher Urbach energies indicated higher local disorder in the glass network. FTIR bands revealed the manifestation of the boron anomaly through the existence of BO
3
, BO
4
units alongside Bi-O and Ge-O vibrations. These glasses are used in non-linear optical uses, infrared absorption, and radiation shielding.