Mixed-alkali effect in Na–Rb borate glasses: A tracer diffusion and electrical conductivity study

2004 ◽  
Vol 6 (13) ◽  
pp. 3669-3675 ◽  
Author(s):  
S. Voss ◽  
Á. W. Imre ◽  
H. Mehrer
Keyword(s):  
Electrical Conductivity ◽  
Tracer Diffusion ◽  
Borate Glasses ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Electrical Conductivity Study

Diffusion and Ionic Conduction in Soda-Lime Silicate Glasses and in Alkali Borate Glasses

2011 ◽  
Vol 312-315 ◽  
pp. 1184-1197
Author(s):  
Helmut Mehrer
Keyword(s):  
Borate Glass ◽  
Ionic Conduction ◽  
Soda Lime ◽  
Tracer Diffusion ◽  
Sodium Borate ◽  
Soda Lime Glass ◽  
Borate Glasses ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Pressure Independent

This paper reviews typical results of tracer diffusion and ionic conduction in soda-lime silicate glass and in single-alkali and mixed-alkali borate glass obtained in our laboratory and published in detail elsewhere. We have studied tracer diffusion of modifier cations and ionic conduction as functions of composition, temperature and, in the case of borate glass, also as function of pressure. We compare tracer diffusion with charge diffusion and in the case of soda-lime glass also with viscosity diffusion. The Haven ratios for soda-lime glass are temperature independent. For sodium borate glass the Haven ratio is almost temperature- and pressure-independent, whereas it decreases significantly with decreasing temperature and increasing pressure for rubidium borate glass. It also decreases with increasing alkali content. We attribute these facts to collective atomic jump events, in which several ions move simultaneously in a string-like or chain-like fashion. We also illustrate the mixed-alkali effect, which was studied by conductivity measurements and by tracer diffusion for mixed sodium-rubidium borate glasses.

scholarly journals The Electrical Conductivity of Some Hydrous and Anhydrous Molten Silicates as a Function of Temperature and Pressure

2021 ◽  
Author(s):  
◽  
John Satherley
Keyword(s):  
Electrical Conductivity ◽  
Quartz Crystal ◽  
Pressure Coefficient ◽  
General Picture ◽  
Water Composition ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Temperature And Pressure ◽  
Increasing Temperature ◽  
Arrhenius Temperature

<p>This thesis is concerned with the measurement and interpretation of electrical conductivity in molten silicates. Physicochemical properties and structural models of silica and silicates are reviewed first, to give a general picture of their behaviour. Electrical conductivity was measured as a function of temperature, pressure and water composition. To make these measurements an internally heated pressure vessel, designed to operate at temperatures up to 1200 degrees C and pressures up to 5 kbars was constructed. Conductivity measurements were made on the following anhydrous and hydrous silicate melts: SiO2/Na2O 60/40, 65/35, 75/25, 78/22 mol%; SiO2/Na2O/CaO 72/24/4 mol%; Mt. Erebus lava; SiO2/Na2O 78/22 mol% + ~5 wt% H2O and Mt. Erebus lava + ~4 wt% H2O in the temperature range 850-1000 degrees C and the pressure range 0-1.3 kbar. Arrhenius temperature and pressure dependencies on conductivity were observed. The pressure coefficient of conductivity was zero for the anhydrous melts well above Tg but small and positive for the hydrous silicates. Water caused ~40% reduction in conductivity when added to a melt which was accounted for in terms of the mixed alkali effect. Conductivity isobars for the hydrous silicates passed through a maximum as a function of increasing temperature. The conductivity behaviour as a function of temperature and pressure is analogous to that observed in partially ionised liquids and is intrepretated in an identical way. The range of operation of a piezoelectric alpha-quartz crystal viscometer was extended to allow measurement of viscosity as a function of temperature.</p>

scholarly journals Mixed-Alkali Effect in Borate Glasses: Thermal, Elastic, and Vibrational Properties

Solids ◽  
2020 ◽  
Vol 1 (1) ◽  
pp. 16-30
Author(s):  
Seiji Kojima
Keyword(s):  
Vibrational Properties ◽  
Borate Glasses ◽  
Lithium Borate ◽  
Cauchy Type ◽  
Oxide Glasses ◽  
Raman Scattering Spectroscopy ◽  
Alkali Ions ◽  
Mixed Alkali ◽  
Mixed Alkali Effect ◽  
Longitudinal Modulus

When oxide glasses are modified by dissimilar alkali ions, a maximum in the electric resistivity or the expansion coefficient appears, called the mixed-alkali effect (MAE). This paper reviews the MAE on the thermal, elastic, and vibrational properties of the mixed-cesium lithium borate glasses, x{(1−y)Cs2O-yLi2O}-(1−x)B2O3. For the single-alkali borate glasses, xM2O(1−x)-B2O3 (M = Li, Na, K, Rb, and Cs), the glass transition temperature, Tg = 270 °C, of a borate glass monotonically increases as the alkali content x increases. However, for the mixed-cesium lithium borate glasses the Tg shows the minimum against the lithium fraction y. The dependences of the elastic properties on the lithium fraction y were discussed regarding the longitudinal modulus, Poisson’s ratio, and Cauchy-type relation. The internal vibrational bands related to the boron-oxide structural groups and the splitting of a boson peak were discussed based on Raman scattering spectroscopy. The MAE on various physical properties are discussed on the basis of the changes in the coordination number of the borons and the nonbridging oxygens caused by the dissimilar alkali ions.

Tracer diffusion in sodium–rubidium borate glassesAn unconventional mixed-alkali effect?

2000 ◽  
Vol 138 (1-2) ◽  
pp. 105-114 ◽  
Author(s):  
Ulrich Schoo ◽  
Cornelia Cramer ◽  
Helmut Mehrer
Keyword(s):  
Tracer Diffusion ◽  
Mixed Alkali ◽  
Mixed Alkali Effect

Mixed alkali effect in 0.2[xKNO3 + (1 − x)NaNO3] + 0.8glycerol systems

1994 ◽  
Vol 72 (11) ◽  
pp. 2286-2290 ◽  
Author(s):  
Sekh Mahiuddin
Keyword(s):  
Electrical Conductivity ◽  
Temperature Dependence ◽  
Mole Fraction ◽  
Linear Functions ◽  
Present System ◽  
Polarization Model ◽  
Mixed Alkali ◽  
Temperature Dependence Of Conductivity ◽  
Mixed Alkali Effect

Density, electrical conductivity, and fluidity of 0.2[xKNO3 + (1 − x)NaNO3] + 0.8glycerol systems were measured as functions of temperature (363.15 to428.15 K) and composition (0.0to 1.0 mole fraction). Densities were linear functions of temperature. The temperature dependence of conductivity and fluidity has been analysed by using the Vogel–Tammann–Fulcher (VTF) equation. Deviation from additivity has been observed in the electrical conductivity, fluidity isotherms to a lesser extent, and in electrical conductivity under isofluidity condition. The onset of the mixed alkali effect (MAE) in the present system has been explained by the anion polarization model.

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