Size effects of modifying cations on the structure and elastic properties of Na2O–MO–SiO2 glasses (M = Mg, Ca, Sr, Ba)

摘要: Abstract The structure and elastic properties of the ternary Na 2 O·MO·4SiO glasses (M = Mg, Ca, Sr, Ba) have been investigated using both Raman Brillouin spectroscopy at ambient conditions. Unlike what observed in binary alkali silicate glasses, symmetric stretching frequencies Q 3 species decrease with increasing size M 2+ cation. When alkaline earth cation decreases, glass becomes more polymerized an increase equilibrium constant for disproportional reaction  ⇌ Q 4  + Q (without balance) if activity coefficients all are independent cations. At given MO concentration, except M = Mg, moduli decreasing . That is, among same group cations period table, higher-field modifying (e.g., Mg ) a does not always cause higher apparent concentration causes these phenomena correlated to local environment degree dissociation oxides O·2SiO glass.