Correlation between physical, structural, thermal and mechanical properties of tellurite TeO${}_2$-BaO-M${}_n$O${}_m$ glasses (M = W, Y, Sr or Li)

The melt quenching technique was used to prepare tellurite glasses with compositions 70TeO${}_2$-20BaO-10WO${}_3$ (BT:W glass), 70TeO${}_2$-20BaO-10Y${}_2$O${}_3$ (BT:Y glass), 70TeO${}_2$-20BaO-10SrO (BT:Sr glass) and 70TeO${}_2$-20BaO-10Li${}_2$O (BT:Li glass). The impact of modifying ions Ba${}^{2+}$, W${}^{6+}$, Y${}^{3+}$, Sr${}^{2+}$, and Li${}^{+}$ on structural, physical, thermal and mechanical properties of the prepared glasses has been explored by using XRD, DTA, and FTIR spectroscopic techniques. XRD analysis conformed that the prepared glasses are amorphous and homogeneous in nature. The FTIR spectra revealed the presence of TeO${}_4$ trigonal bipyramids, TeO${}_3$ trigonal pyramids and NBOs in the network of BT:Y, BT:Sr and BT:Li glasses. Meanwhile, the structure of BT:W glass is composed of TeO${}_4$, TeO${}_3$, WO${}_4$ and WO${}_6$ units, which are connected to each other through W-O-Te linkages. The glass transition temperature and thermal stability increased in the order BT:W glass > BT:Y glass > BT:Sr glass > BT:Li glass. These results were compared to those of binary 80TeO${}_2$-20BaO glass (BT) and pure TeO${}_2$ glass. Changes in the thermal properties have been analyzed and predicted by correlating them with the calculated molar volume, ratio of packing density to mean atomic volume, dissociation energy per unit volume, field strength of the modifying ions, average single bond strength, and elastic moduli. The R-squared values of the regression lines can be improved if the effect of all structural groups as well as the uncertainty inherent in experimental measurements are taken into account. The highest thermal stability and glass transition temperature of BT:W glass making it a good candidate for shielding material in the fields of medical, industrial, and nuclear applications.