Abstract
The doping influence of niobium pentoxide (Nb
2
O
5
) on the structure, physical, FTIR, and optical properties of new synthesized glass systems of the calcium zinc borate glasses with chemical formula 60B
2
O
3
·25CaO·15ZnO·xNb
2
O
5
: 0 ≤ x ≤ 1 mol% has been investigated. The BCZNbx samples were synthesized using the melt quenching technique. XRD measurements were used to confirm the noncrystalline structure of the prepared glasses. The density (ρ) gradually increased from 3.261 to 3.312 g/cm
3
and molar volume (V
m
) from 20.849 to 21.335 cm
3
/mol for BCZNb0.0 to BCZNb1.0 glasses, respectively. The oxygen molar volume (OMV) reduced nonlinearly from 9.81 to 9.68 cm
3
/mol as the Nb
2
O
5
mol% increasing followed a reverse trend of (ρ) and (V
m
). The oxygen packing density (OPD) increased from 101.91 to 103.26 g.atom/l. The estimated optical band gap (
E
g
) values were 3.66 (± 0.01), 3.61 (± 0.01), 3.57 (± 0.01), and 3.55 (± 0.01) eV for the 0 mol%, 0.2 mol%, 0.6 mol%, and 0.8 mol% of Nb
2
O
5
contents, respectively. Values of linear refractive index (n
0
) showed a very slight increment from 2.26 to 2.29 with further additions Nb
2
O
5
, while nonlinear one (n
2
) showed an increase from 2.26 × 10
–11
(at 0 mol% of Nb
2
O
5
content) to 2.53 × 10
–11
(at 0.8 mol% of Nb
2
O
5
content). FTIR measurements reflected that relative fraction of BO
4
(P4) decreases while relative fraction of BO
3
(P3) increases by Nb
2
O
5
doping. Such a result confirmed that the Nb ions cause a variation in borate structural coordination and partially back conversion from [BO
4
] to [BO
3
] units in the glass network.