Influence of pressure on the refractive index and relative density of glasses in the CaO-Al2O3-SiO2 system

Abstract

The pressure dependences of the refractive index for aluminosilicate glasses of the compositions 0.167CaO · 0.167Al 2 O 3 · 0.666SiO 2 and 0.157CaO · 0.177Al 2 O 3 · 0.666SiO 2 at pressures up to 6.0 GPa are determined using a polarizing interference microscope and an apparatus with diamond anvils. The compressibilities of the glasses are calculated from the measured refractive indices within the framework of the theory of photoelasticity. The structural-chemical parameters NBO / T (where NBO is the number of gram-ions of nonbridging oxygen atoms and T is the total number of gram-ions of network formers) are calculated for the glasses under investigation with allowance made for the formation of triclusters and highly coordinated aluminum.

Effect of alkaline and alkaline-earth cations on the compressibility of aluminosilicate glasses

“…2 shows the linear approximation of dependencies of relative changes in density (d-d 0 )/d on the degree of depolymerization NBO/T for glasses of the system СaO•Al 2 O 3 •xSiO 2 (x=2, 4, 6) at Р = 3, 4 and 5 GPa. The values of the relative change in density and the degree of depolymerization were obtained and calculated in Kuryaeva, 2008;2009;Kuryaeva et al, 2007;. If the degrees of depolymerization are estimated correctly, these dependencies must, most likely, be appropriate for glasses of the system Na 2 O•Al 2 O 3 •xSiO 2 .…”