Structural and mechanical properties of zinc aluminoborate glasses with different content of aluminum oxide

The glass samples were prepared according to the following formula: (35 - x) ZnO, 55B(2)O(3), 10Li(2)O, x Al2O3, where (x = 0.5; 1; 1.5; 2; 2.5; 3; 3.5; 4 mol%) by melt quenching method. Structural parameters such as density, molar volume, cation-anion bond length, and packing density were studied and were correlated to the structural changes. It is found that the density decreases and the molar volume increases with increasing Al2O3 content. FT-IR spectra were measured to investigate the glass structure of these samples and to confirm the formation of non bridging Al-O-B bond with the addition of Al2O3 content. The FT-IR spectra were deconvoluted using curves of Gaussian shape at approximately the same frequencies. The fraction of fourfold coordinated boron atom (N-4) was calculated from the deconvoluted data. The longitudinal and transverse ultrasonic wave velocities were measured using the pulse-echo technique. The longitudinal L, shear S, Young's E and bulk B module were calculated from the measured velocity and density values of the prepared samples and were correlated with the structural changes and all reflects that addition of Al2O3 to present glasses results in de-polymerization of the glass network and formation of non-bridging oxygen (NBOs).