Properties and structure of (1-x)Li2O-xNa2O-Al2O3-4SiO2 glass systems

(1 - x)Li2O-xNa(2)O-Al2O3-4Si0(2) glasses were studied for the progressive percentage substitution of Na2O for Li2O at the constant mole of Al2O3 and SiO2. The crystallization temperature at the exothermic peak increased from 898 to 939 degrees C when the NaO content increases from 0 to 0.6 mol. The coefficient of thermal expansion and density of these as-quenched glasses increase from 6.54 X 10(-6) degrees C-1 to 10.1 X 10(-6) degrees C-1 and 2.378 g cm(-3) to 2.533 g cm(-3) when the Na2O content increases from 0 to 0.4 mol, respectively. The electrical resistivity has a maximum value at Na2O center dot (Li2O + Na2O)(-1) = 0.4. The activation energy of crystallization decreases from 444 to 284 kJ mol(- 1) when the Na2O content increased from 0 to 0.4 mol. Moreover, the activation energy increases from 284 kJ mol(- 1) to 446 kJ mol(-1) when the Na2O content increased from 0.4 to 0.6 mol. The FT-IR spectra show that the symmetric stretching mode of the SiO4 tetrahedra (1035-1054 cm(-1)) and AlO4 octahedra (713-763 cm(-1)) exhibiting that the network structure is built by SiO4 tetrahedra and AlO4. (c) 2006 Published by Elsevier B.V.