Structural features of calcium-borosilicate glasses

Investigation on the near-infrared-emitting thermal stability of Bi activated alkaline-earth aluminoborosilicate glasses

“…For instance, it was found that in aluminoborosilicate glasses, 28,29 alkaline cations were preferentially involved in charge compensation of (AlO 4 ) and (BO 4 ) entities in the glassy network comparative to alkaline-earth cations, which enhanced the content of rigid BO 4 and AlO 4 tetrahedral and decreased mesh size of glass matrix consequently. Moreover, as for alkaline-earth aluminoborosilicate glasses, such effects have also been known from previous studies, [30][31][32] where Ca 2þ has been described as having a greater effect on "depolymerizing" the borosilicate network than Sr 2þ and Ba 2þ ions. The above results mean the structure rigidity may be insufficient for understanding the thermally treated NIR-emitting performance of SBAR glasses.…”

Effects of cation field strength on the structure of aluminoborosilicate glasses: High-resolution 11B, 27Al and 23Na MAS NMR

“…4 summarizes the major effects of increasing CaO/Na 2 O ratio on decreasing N 4 and increasing NBO contents for our samples with two different ratios of SiO 2 /B 2 O 3 . Such effects are known in general from previous studies, where Ca 2+ has been described as having a greater effect on 'depolymerizing' the borosilicate network [3,42,64]. In these systems, higher field strength modifier cations favor the formation of highly charged NBO, over the lower charged bridging oxygens that form linkages such as [4] B-O- [4] Si, thus shifting reaction (3) to the left.…”

The influence of calcium oxide on the60Co-γ ray irradiation resistance of Ce-doped (alumino-) borosilicate glass

“…Calcium cation Ca 2+ has two positive charges, so its capability of trapping an electron is stronger than that of sodium cation Na + , so Ca 2+ may increase the irradiation-induced trapped electron center. It is known that three-coordinated boron (aluminum) always forms a dipolar bond with a non-bridging oxygen in glass and turns four-coordinated (11), as the left part of Figure 3 shows. Irradiation induces more E 1 center in the (alumino-) borosilicate glass doped with alkaline earth metal oxides because the calcium cation polarizes and weakens the Si-O bond signed in Figure 3, and makes them vulnerable, so irradiation more easily breaks the Si-O bonds in the glasses and produces more E 1 centers, as shown in the right part of Figure 3 (the part red dash line boxed is E 1 center).…”