Influence of BaTiO3 on physical and optical studies of Na2B4O7-MoO3-TeO2 glasses reinforced with vanadium ions

Glasses with the compositions xBaTiO(3)-(78-x)Na2B4O7-10MoO(3)-10TeO(2)-2V(2)O(5) with (x = 0, 5, 10, 15 and 20 mol%) named as [BNMTV-1(x = 0), BNMTV-2(x = 5), BNMTV-3(x = 10), BNMTV-4(x = 15) and BNMTV-5(x = 20)], were prepared by melt-quenching process. BaTiO3 gradually replaces Na2B4O7, while the other elements remain unchanged. To prove the amorphous phase, XRD measurements were taken. The density of the produced glasses grows as the amount of BaTiO3 increases while the molar volume declines. The crystal density of BaTiO3 is 6.023 gm/cc, and it is much greater than the Na2B4O7 crystal density (2.367 gm/cc) that might be the reason for the density increment. Highly denser BNMTV-5 is most suitable for radiation shielding applications. Refractive indices decline from 2.405 [BNMTV-1] to 2.383 [BNMTV-5] glass sample. All the glass samples have high refractive index values suitable for core material in optical fibres. BNMTV-1 is the proper glass for the core material in optical fibre. The decrease in molar volume is supplemented by the decrease of boron-boron separation and interatomic distance with the increase of BaTiO3 concentration. The polaron radius and field strength are showing opposite behaviour, as expected. From optical absorption spectra, the optical energy gap E-opt and Urbach energy values were estimated. On increasing BaTiO3, E-opt values are slightly increasing. From the optical bandgap (E-opt) values the refractive index, dielectric constant, etc., were evaluated. FTIR spectra indicated the presence of various molybdate MoO4, MoO6 and Mo2O7 groups along with triangular BO3 and BO4 tetrahedra. Raman spectra also confirmed the presence of molybdate groups along with various borate units. The EPR spectra revealed the hyperfine structure of VO2+ ions and these ions are in tetragonally compressed octahedral site with C-4v symmetry.

Automated summary

Glasses with varying BaTiO3 compositions were prepared by melt-quenching process, showing increased density and decreased molar volume as BaTiO3 content increased. These glasses are suitable for radiation shielding and optical fiber core material.