A study of the mixed alkali effect by frequency-dependent conductivity in Li2O-Na2O-P2O5 glasses

Chen, Rongmei; Yang, Ruizhi; Durand, Benjamin; Pradel, Annie; Ribes, M.

doi:10.1016/0167-2738(92)90312-d

Cited by 31 publications

(16 citation statements)

References 6 publications

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“…The mixed alkali phenomenon, which from a practical viewpoint is useful in manufacturing low-loss electrical glass and in understanding chemical strengthening of glass [1], is not completely understood, thereby necessitating further in-depth characterizations of mixed alkali materials. The origins of the mixed-alkali effect have been explored through measurements of dielectric and mechanical properties [3,[7][8][9] and via spectroscopic techniques including Raman [10], X-ray absorption [11,12], and nuclear magnetic resonance (NMR) [13][14][15][16][17]. Theoretical tools have also been brought to bear, and molecular dynamics [18][19][20] and Monte Carlo [21] simulations provide models of the spatial distributions of mixed-alkali ions.…”

Section: Introductionmentioning

confidence: 99%

Solid-state NMR investigations of sodium–cesium mixed-alkali phosphate glasses

Prabakar

Mueller

2004

Journal of Non-Crystalline Solids

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Section: Introductionmentioning

confidence: 99%

Solid-state NMR investigations of sodium–cesium mixed-alkali phosphate glasses

Prabakar

Mueller

2004

Journal of Non-Crystalline Solids

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“…The thermal behavior of mixed‐alkali glasses has been debated, with several authors reporting no significant deviation from additivity in heat capacity or structural relaxation data 59‐61 or, in the case of Shelby, pointing out that similar nonlinear behaviors occur in mixed‐former glasses without any alkali added 62 . Nonetheless, those authors 59‐62 and others 63,64 have reported a significant deviation in T g values for mixed‐alkali glasses, and many older papers discuss a decrease of one to two orders of magnitude in viscosity 4,65 . In contrast to structural studies which report only linear changes in the structure of mixed‐alkali glasses, 5,27,28 this substantial decrease in T g has been related to an increase in the number of NBOs and a change in the coordination number of the cations 63,66 —clear structural modifications that might be expected to have manifestations in the relaxation behavior.…”

Section: Resultsmentioning

confidence: 99%

Influence of glass network ionicity on the mixed‐alkali effect

Calahoo

Xia

Zhou

2020

Int J of Appl Glass Sci

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Most studies of the mixed-alkali effect (MAE) have focused on relating the differences between the cations to the strength of the MAE; here we examine the effect of the glass former by comparing the MAE in aluminofluorophosphate (FP) and aluminosulfofluorophosphate (FPS) glasses. The sulfate anion in the FPS series does not bond directly to the aluminophosphate network, decreasing connectivity and increasing the ionicity of the FPS glasses. The increased degrees of freedom imparted by the sulfate are evident in the single-alkali FPS glasses, which have lower E a , hardness, shear moduli, and Young's moduli, and higher T g than the corresponding single-alkali FP glasses (without sulfate). Conversely, for the mixed-alkali FPS compositions, the sulfate's mobility is reduced by the mixed cations, resulting in a magnified MAE for the FPS series. For dynamic properties, this phenomenon is explained by reduced plasticity and slippage along ion channels, while understanding T g and elastic properties requires examination of the shape of the sulfate's potential energy well and the resulting regions of compressive and tensile stress. We posit that glass compositions with higher plasticity, that is, less covalent bonding, will exhibit a larger MAE, but, simultaneously, sufficient conventional glass network must be present to constrain the mobile ions.

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“…Previous conductivity MAE studies based on phosphate and borate network formers have been reported for the glasses with two and three types of alkali ions systems in the temperature range 240-523 K [4,5,12,13]. The strength of MAE is strongly dependent on the annealing temperature and alkali element.…”

Section: Introductionmentioning

confidence: 98%