(FR2758550-A1)      A glass composition, for making thermally stable substrates or plates, contains (by wt.) 55-70 (preferably 55-60) % SiO2, 0-3 (preferably 0-1) % B2O3, 2-6 (preferably 3-5) % Na2O, 5-11 (preferably 5-9) % K2O, 0-6 (preferably 1-6) % MgO, 2-11 (preferably 7-11) % CaO, 4-12 (preferably 6-10) % SrO, 0-2 (preferably 0-1 or 1-2) % BaO, more than 0 and 0.5 (preferably 0.005-0.15) % SO3 and either (a) 0-5 (preferably 1-4) % Al2O3 and 5-10 (preferably 6-9) % ZrO2 or (b) 0-5 (preferably 1-4) % ZrO2 and 5-10 (preferably 6-9) % Al2O3. Na2O+K2O 8% (preferably 10-15%). MgO+CaO+SrO+BaO&gt;10% (preferably 15%). Composition (a) has a lower strain point temperature of above 600C and composition (b) has a lower strain point temperature of above 570 (preferably above 580 or 600)C.    USE -   Used for producing: (i) barium sulphate crystal-free substrates for emissive screens of plasma screen, electroluminescent screen or cold cathode screen type, especially from a glass sheet cut from a float glass ribbon; (ii) fire resistant glazing, especially from a glass plate or sheet cut from a float glass ribbon; and (iii) solar energy conversion systems of photovoltaic cell type (all claimed).    ADVANTAGE -   The glass composition can be subjected to the requisite conventional heat treatments above 500C without optical degradation, especially local yellow discolouration caused by barium sulphate crystal formation. Additionally, the glass composition has a thermal expansion coefficient (25-300C) of 80-90x10-7 (especially 82-86x10-7)/C, a liquidus temperature of 1180 (especially 1150-1170)C, a viscosity (in poises) corresponding to log = 3.5 at 1160 (especially 1160-1200)C, a resistivity (in .cm, at 250C) corresponding to log = 9 (especially 9-11) and a density (at 25C) of &lt;3 (especially ca. 2.7).    (JP10291833-A)      A glass composition, for making thermally stable substrates or plates, contains (by wt.) 55-70 (preferably 55-60) % SiO2, 0-3 (preferably 0-1) % B2O3, 2-6 (preferably 3-5) % Na2O, 5-11 (preferably 5-9) % K2O, 0-6 (preferably 1-6) % MgO, 2-11 (preferably 7-11) % CaO, 4-12 (preferably 6-10) % SrO, 0-2 (preferably 0-1 or 1-2) % BaO, more than 0 and 0.5 (preferably 0.005-0.15) % SO3 and either (a) 0-5 (preferably 1-4) % Al2O3 and 5-10 (preferably 6-9) % ZrO2 or (b) 0-5 (preferably 1-4) % ZrO2 and 5-10 (preferably 6-9) % Al2O3. Na2O+K2O 8% (preferably 10-15%). MgO+CaO+SrO+BaO&gt;10% (preferably 15%). Composition (a) has a lower strain point temperature of above 600C and composition (b) has a lower strain point temperature of above 570 (preferably above 580 or 600)C.    USE -   Used for producing: (i) barium sulphate crystal-free substrates for emissive screens of plasma screen, electroluminescent screen or cold cathode screen type, especially from a glass sheet cut from a float glass ribbon; (ii) fire resistant glazing, especially from a glass plate or sheet cut from a float glass ribbon; and (iii) solar energy conversion systems of photovoltaic cell type (all claimed).    ADVANTAGE -   The glass composition can be subjected to the requisite conventional heat treatments above 500C without optical degradation, especially local yellow discolouration caused by barium sulphate crystal formation. Additionally, the glass composition has a thermal expansion coefficient (25-300C) of 80-90x10-7 (especially 82-86x10-7)/C, a liquidus temperature of 1180 (especially 1150-1170)C, a viscosity (in poises) corresponding to log = 3.5 at 1160 (especially 1160-1200)C, a resistivity (in .cm, at 250C) corresponding to log = 9 (especially 9-11) and a density (at 25C) of &lt;3 (especially ca. 2.7).    (US6063718-A)      A glass composition, for making thermally stable substrates or plates, contains (by wt.) 55-70 (preferably 55-60) % SiO2, 0-3 (preferably 0-1) % B2O3, 2-6 (preferably 3-5) % Na2O, 5-11 (preferably 5-9) % K2O, 0-6 (preferably 1-6) % MgO, 2-11 (preferably 7-11) % CaO, 4-12 (preferably 6-10) % SrO, 0-2 (preferably 0-1 or 1-2) % BaO, more than 0 and 0.5 (preferably 0.005-0.15) % SO3 and either (a) 0-5 (preferably 1-4) % Al2O3 and 5-10 (preferably 6-9) % ZrO2 or (b) 0-5 (preferably 1-4) % ZrO2 and 5-10 (preferably 6-9) % Al2O3. Na2O+K2O 8% (preferably 10-15%). MgO+CaO+SrO+BaO&gt;10% (preferably 15%). Composition (a) has a lower strain point temperature of above 600C and composition (b) has a lower strain point temperature of above 570 (preferably above 580 or 600)C.    USE -   Used for producing: (i) barium sulphate crystal-free substrates for emissive screens of plasma screen, electroluminescent screen or cold cathode screen type, especially from a glass sheet cut from a float glass ribbon; (ii) fire resistant glazing, especially from a glass plate or sheet cut from a float glass ribbon; and (iii) solar energy conversion systems of photovoltaic cell type (all claimed).    ADVANTAGE -   The glass composition can be subjected to the requisite conventional heat treatments above 500C without optical degradation, especially local yellow discolouration caused by barium sulphate crystal formation. Additionally, the glass composition has a thermal expansion coefficient (25-300C) of 80-90x10-7 (especially 82-86x10-7)/C, a liquidus temperature of 1180 (especially 1150-1170)C, a viscosity (in poises) corresponding to log = 3.5 at 1160 (especially 1160-1200)C, a resistivity (in .cm, at 250C) corresponding to log = 9 (especially 9-11) and a density (at 25C) of &lt;3 (especially ca. 2.7).    (TW416936-A)      A glass composition, for making thermally stable substrates or plates, contains (by wt.) 55-70 (preferably 55-60) % SiO2, 0-3 (preferably 0-1) % B2O3, 2-6 (preferably 3-5) % Na2O, 5-11 (preferably 5-9) % K2O, 0-6 (preferably 1-6) % MgO, 2-11 (preferably 7-11) % CaO, 4-12 (preferably 6-10) % SrO, 0-2 (preferably 0-1 or 1-2) % BaO, more than 0 and 0.5 (preferably 0.005-0.15) % SO3 and either (a) 0-5 (preferably 1-4) % Al2O3 and 5-10 (preferably 6-9) % ZrO2 or (b) 0-5 (preferably 1-4) % ZrO2 and 5-10 (preferably 6-9) % Al2O3. Na2O+K2O 8% (preferably 10-15%). MgO+CaO+SrO+BaO&gt;10% (preferably 15%). Composition (a) has a lower strain point temperature of above 600C and composition (b) has a lower strain point temperature of above 570 (preferably above 580 or 600)C.    USE -   Used for producing: (i) barium sulphate crystal-free substrates for emissive screens of plasma screen, electroluminescent screen or cold cathode screen type, especially from a glass sheet cut from a float glass ribbon; (ii) fire resistant glazing, especially from a glass plate or sheet cut from a float glass ribbon; and (iii) solar energy conversion systems of photovoltaic cell type (all claimed).    ADVANTAGE -   The glass composition can be subjected to the requisite conventional heat treatments above 500C without optical degradation, especially local yellow discolouration caused by barium sulphate crystal formation. Additionally, the glass composition has a thermal expansion coefficient (25-300C) of 80-90x10-7 (especially 82-86x10-7)/C, a liquidus temperature of 1180 (especially 1150-1170)C, a viscosity (in poises) corresponding to log = 3.5 at 1160 (especially 1160-1200)C, a resistivity (in .cm, at 250C) corresponding to log = 9 (especially 9-11) and a density (at 25C) of &lt;3 (especially ca. 2.7).