caa a22 4500 463190475 CHVBK 20180406164907.0 cr unu---uuuuu 170326e20071101xx s 000 0 eng 10.1007/s10973-006-7976-5 doi (NATIONALLICENCE)springer-10.1007/s10973-006-7976-5 Viscosity and structural relaxation of 15Na2O· x MgO·(10− x )CaO·75SiO2 glasses [Elektronische Daten] [Mária Chromčiková, M. Liška] Temperature dependence of viscosity of title glasses (x=0, 2, 4, 6, 8, 10, abbreviated as M0, M2, M4, M6, M8, and M10, respectively) was measured by rotational viscometry (high temperature region: 102−106.5 dPas) and thermomechanical analysis (low temperature region: 108.5−1011.5 dPas) and described by the Vogel-Fulcher-Tammann equation. The MgO/CaO equimolar substitution (i.e. the increasing x value) smoothly shifts the high temperature viscosity to higher values. In the low temperature region the mixed alkali effect is demonstrated, and the highest viscosities are observed for the glasses M0 and M10. In the low temperature range the activation energy of viscous flow linearly decreases with the increasing x value (E act/kJ mol−1=479−9.0x). No significant dependence of activation energy on x was found in the high temperature range (E act/kJ mol−1=238.1±4.2). The structural relaxation was measured by thermomechanical experiment and theoretically interpreted in the frame of Tool-Narayanaswamy-Mazurin's model. The broadening of the relaxation time spectrum was observed for the calcium-magnesium glasses in comparison with the pure calcium or magnesium glasses. Springer Science+Business Media, LLC., 2007 glass nationallicence glass transition nationallicence relaxation phenomena nationallicence thermomechanical analysis nationallicence Chromčiková Mária Vitrum Laugaricio (VILA) — Joint Glass Center of the Institute of Inorganic Chemistry SAS, Alexander Dubček University of Trenčín, and RONA Lednické Rovne, Študentská 2, 911 50, Trenčín, Slovak Republic aut Liška M. Vitrum Laugaricio (VILA) — Joint Glass Center of the Institute of Inorganic Chemistry SAS, Alexander Dubček University of Trenčín, and RONA Lednické Rovne, Študentská 2, 911 50, Trenčín, Slovak Republic aut Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/2(2007-11-01), 421-429 1388-6150 90:2<421 2007 90 10973 https://doi.org/10.1007/s10973-006-7976-5 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10973-006-7976-5 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Chromčiková Mária Vitrum Laugaricio (VILA) — Joint Glass Center of the Institute of Inorganic Chemistry SAS, Alexander Dubček University of Trenčín, and RONA Lednické Rovne, Študentská 2, 911 50, Trenčín, Slovak Republic aut NATIONALLICENCE 700 1- Liška M. Vitrum Laugaricio (VILA) — Joint Glass Center of the Institute of Inorganic Chemistry SAS, Alexander Dubček University of Trenčín, and RONA Lednické Rovne, Študentská 2, 911 50, Trenčín, Slovak Republic aut NATIONALLICENCE 773 0- Journal of Thermal Analysis and Calorimetry Springer US; http://www.springer-ny.com 90/2(2007-11-01), 421-429 1388-6150 90:2<421 2007 90 10973 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer