Effect of High Pressure on the Refractive Index and Density of Natural Aluminosilicate Glasses of Alkali Basalt Composition in the SiO_2-Al_2O_3-TiO_2-Fe_2O_3-P_2O_5-FeO-MnO-CaO-MgO-Na_2O-K_2O System

摘要

The pressure dependence of the refractive index for a natural glass of composition 0.528SiO_2centre dot 0.019TiO_2 centre dot 0.102A1_2O_3 centre dot 0.021Fe_2O_3 centre dot 0.062FeO centre dot 0.002MnO centre dot 0.081CaO centre dot 0.072MgO centre dot 0.068Na_2O centre dot 0.034K_2O centre dot 0.011P_2O_5 at pressures up to 5.0 GPa is determined using a polarizing interference microscope and an apparatus with diamond anvils.The densities and compressibilities of the glass are calculated from the measured refractive indices within the theory of photoelasticity.The results are compared with the data obtained earlier for another glass that has a similar composition but contains a lower concentration of alkali metal oxides.A higher compressibility of the glass under investigation as compared to the compressibility of the glass studied previously is in agreement with the degrees of polymerization that are calculated taking into account the formation of triclusters.