The electrical conductivity of lithium phosphate glasses has been studied over wide frequency and temperature ranges, using a fully automated system capable of yielding data of high precision. Due to a “total drybox” sample preparation facility, samples containing P2O5 contents up to 65 mol% have been included without sacrifice of data quality. Comparisons with the behavior of the corresponding silicate, borate and boroaluminate glasses have been made and analyzed in terms of microscopic models. At the other composition extreme, measurements have been extended to 62.5 mol% Li2O without finding a conductivity maximum. The ac conductivity data have been analyzed using the modulus formalism, and systematic trends in the Kohlrausch parameter β with composition have been recorded. β decreases from 0.60 to 0.49 over the composition range 37–62.5 mol% li2O and seems to correlate best with the isothermal conductivity. Attention is drawn to anomalous structuring effects in P2O5-rich glasses.

Dc and ac conductivity in wide composition range Li2OP2O5 glasses

Dissolution kinetics of quartz in sodium chloride solutions: Analysis of existing data and a rate model for 25°C

Gel technology in ceramics

A frequency independent or nearly frequency independent contribution to the dielectric loss is present in all ionic conductors independent of the chemical and physical structures. An exhaustive collection of dielectric relaxation data of glassy, crystalline, and molten ionic conductors are analyzed to obtain the magnitudes of their constant losses and the dependencies on temperature, ion density, ion mass, dc conductivity activation energy, dc conductivity level, the nonexponential conductivity relaxation parameter β, the mixed alkali effect, and the decoupling index Rτ. Trends of changes in the constant loss when modifying the structure of the glassy matrix or mixing two different alkali ions are also found. In a glass-forming molten salt, 0.4Ca(NO3)2⋅0.6KNO3, the constant loss turns out to have approximately the same temperature dependence as the mean square displacement of the ions obtained by elastic neutron scattering measurement. All dependencies and properties found indicate that the physical origin of the constant loss may be traced to the displacement of the ions in their local librational or vibrational motion, but anharmonicity is not a necessary ingredient.

Properties of the constant loss in ionically conducting glasses, melts, and crystals

Rapid progress has been made in the last decade in the area of the fundamental mechanisms of electrical relaxation and ionic transport in ionically conducting glasses. Many new experimental findings and computer simulations have become available during this period. These more recent developments should not be viewed as overshadowing the importance of earlier works. Instead, many earlier works, having laid the foundation and paved the way for the recent developments, are of immense importance. The phenomenologies that have been firmly established and the critical experimental facts which have been found will be the subjects of this review. One purpose of this work is to promote interest and debate among workers in this field. Hopefully, this will lead to some consensus among workers in the field on a list of critical experimental facts. For theories proposed in the future, these critical experimental facts can be employed collectively as an acid test of whether the theory is viable.

A review of critical experimental facts in electrical relaxation and ionic diffusion in ionically conducting glasses and melts

Aqueous corrosion studies of a fluorozirconate glass

Borosilicate glasses with high silica and varying water content were made by a process similar to that of Vycor. Dielectric relaxation measurements show a de-conduction activation energy equal to that of fused silica, no apparent dependence of the dc conductivity on water content, and an unexpectedly narrow relaxation-time distribution equivalent to a simple RC circuit element. A single relaxation process is observed in all samples regardless of water content and neither the conductivity nor the activation energy are significantly altered by a 50-fold change in water content.

Dielectric Relaxation in High‐Silica Borosilicate Glasses

The low-frequency conductivity of silica glasses containing 5% B2O3 and from 0.02 to 6.7% Na2O is extrapolated to dc values and analyzed in terms of temperature and concentration dependence. The concentration dependence of the conductivity occurs exclusively in the activation enthalpy. This prevents an analysis of the number of ions participating in the conduction in all but one sample for which tracer diffusion data gave a correlation factor of unity in the Nernst-Einstein equation. The concentration dependence of the activation enthalpy was analyzed empirically. The activation enthalpy varies linearly with sodium-sodium separation or jump distance. This result suggests that, at low Na concentrations, the conducting ions execute several separate motions between nonequilibrium sites before reaching the nearest equivalent site. The empirical equation is shown to fit activation energy data for silica glasses containing from 0.06 to 40% Na2O.

Catherine J. Simmons

Papers

Aqueous corrosion studies of a fluorozirconate glass

Dielectric Relaxation in High‐Silica Borosilicate Glasses

Conductivity Behavior of High‐Silica Glasses with Varied Concentrations of Sodium Ions

Ion‐Exchange Method for Fabricating High‐Silica Glasses

Ion-exchange method for fabricating high-silica glasses