scholarly journals Influence of glass network ionicity on the mixed‐alkali effect

2020 ◽  
Vol 11 (3) ◽  
pp. 396-414
Author(s):  
Courtney Calahoo ◽  
Yang Xia ◽  
Ru Zhou
1985 ◽  
Vol 61 ◽  
Author(s):  
J. N. Mundy ◽  
G.-L. Jin

ABSTRACTThe lack of general applicability of the many theoretical models for the mixed alkali effect (MAE) in glasses is briefly reviewed. Although the MAE appears to be related to the bonding affinity of alkali ions to charge compensating centers in the glass network, experimental scatter and the difficulty of comparing different glass networks have prevented systematic tests of this relationship. The present paper discusses why the mixed alkali germanate glasses should provide a glass system where the concentration and strength of charge-compensating centers can be systematically varied and the relationship to the MAE tested. Such tests are only possible if the ionic conductivity of a series of mixed alkali germanate glasses can be measured in a reproducible manner. The measurements of the ionic conductivity of two series of X(Na,Rb)2O:(1-X)GeO2 glasses, with X = 0.19 and X = 0.29, respectively, suggest the necessary reproducibility can be attained.


2013 ◽  
Vol 22 ◽  
pp. 278-283
Author(s):  
A. EDUKONDALU ◽  
M. A. SAMEE ◽  
SHAIKH KAREEM AHMMAD ◽  
SAIR MD. TAQIULLAH ◽  
SYED RAHMAN ◽  
...  

Mixed alkali tungsten borate glasses xLi2O–(30–x) K2O–10WO3–60B2O3 (0 < x < 30) were prepared from the melts. These glasses were characterized using X-ray diffraction, differential scanning calorimetry and density measurements. Optical absorption studies were carried out as a function of alkali content to look for mixed alkali effect (MAE) on the spectral properties of these glasses. From the study of ultraviolet absorption edge, the optical band gap energies and Urbach energies were evaluated. The average electronic polarizability of the oxide ion, optical basicity and the interaction parameters were also evaluated for all the glasses. Many of these parameters vary non-linearly exhibiting a minima or maxima with increasing alkali concentration, indicating the mixed alkali effect. An attempt is made to interpret MAE in this glass system in terms of its glass structure.


2013 ◽  
Author(s):  
M. Sudhakara Reddy ◽  
Asha Rajiv ◽  
V. C. Veeranna Gowda ◽  
R. P. S. Chakradhar ◽  
C. Narayana Reddy

2000 ◽  
Vol 62 (6) ◽  
pp. 8790-8793 ◽  
Author(s):  
Junko Habasaki ◽  
Yasuaki Hiwatari

2021 ◽  
Author(s):  
◽  
John Satherley

<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>


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