A. A. Pronkin

Electrical properties and the structure of halogen-containing lead borate glasses: I. The PbF2-2PbO.B2O3 system

The temperature and concentration dependences of the dc electrical conductivity of glasses in the PbF2–PbO · B2O3 system are investigated. It is found that the dependences logσ = f([PbF2]) and Eσ = f([PbF2]) for glasses containing ∼20 and ∼35 mol % PbF2 exhibit kinks, which are interpreted from the standpoint of the microinhomogeneous structure associated with the selective interaction of the components during the synthesis of glasses. Analysis of the transport numbers has revealed that the unipolar fluorine ionic conductivity is observed upon introduction of more than 35 mol % PbF2. It is shown that, in the concentration range from 0 to 35 mol % PbF2, the electric current is provided by both protons and fluorine ions.

Structure and electrical conductivity of Li2O-B2O3 glasses

The temperature-concentration dependence of the electrical conductivity of Li2O-B2O3 glasses in the temperature range of ∼180–310°C has been studied. For pure boron anhydride, the dependence logσ = f([1/T]) is linear, whereas for glasses with ∼2 mol % ≤ [Li2O] < ∼10 mol %, similar curves are kinked. At higher Li2O concentration the kinks disappear. Occurrence of kinks is attributed to variation of essence of current carriers from proton pattern for B2O3 to mixed proton-ion pattern for low-alkali glasses. Conductivity of glasses at [Li2O] ≥ 20 mol % is stipulated by the formation of a continuous sublattice of polar structuralchemical entities (entities) [BO4/2]−Li+ and the migration of lithium ions.

A Study of Ionic Conductivity of Glasses in the PbCl2–PbO · B2O3 and PbCl2–2PbO · B2O3 Systems

The steady-state electrical conductivity of oxychloride glasses in the PbCl2–PbO · B2O3 and PbCl2–2PbO · B2O3 systems is investigated. In the temperature range from ∼190 to ∼380°C, the dependence of logσ on the reciprocal of the temperature exhibits a linear behavior. The nature of charge carriers is studied using the Hittorf technique. It is demonstrated that protons and chlorine ions are charge carriers in solid glasses. The concentration dependence of the transport numbers of chlorine ions is examined by the Tubandt method. The contribution of the electronic component to the total electrical conductivity is estimated with the use of the Liang–Wagner technique. The concentration dependences of the electrical conductivity and the transport numbers of chlorine ions are interpreted in terms of the microinhomogeneous glass structure associated with the selective interaction of components during synthesis of glasses.

The nature of charge carriers and their transport numbers in glasses of the Ag2O-B2O3 system

The temperature-concentration dependence of the dc electrical conductivity of glasses in the xAg2O-(1 − x)B2O3 (0.05 ≤ x ≤ 0.25) system is investigated using active (amalgam) electrodes. A series of glasses are synthesized with the use of D2O as an isotope tracer. The analysis of data on the electrolysis of glasses at 0.15 ≤ x ≤ 0.225 demonstrates that charge carriers in these glasses involve protons formed upon dissociation of impurity water. The water content is evaluated by IR spectroscopy. The electronic component of the total electrical conductivity is determined by the Liang-Wagner technique. It is shown that the contribution of the electronic component does not exceed the sensitivity of the technique (10−2—10−3%). The participation of silver ions in electricity transport processes is studied by the Hittorf method. It is demonstrated that their transport numbers do not exceed 0.53. A comparison of the physicochemical properties of glasses in the Ag2O-B2O3 and Na2O-B2O3 systems shows that sodium and silver ions occupy different positions in the structure.

Electrical Properties and the Structure of Glasses in the xNa2O–(1 – x)2PbO · B2O3 System

The temperature–concentration dependences of the electrical conductivity and the activation energy for electrical conduction of glasses in the Na2O–B2O3 and Na2O–2PbO · B2O3 systems are studied. The investigation into the nature of the electrical conduction in these glasses reveals that the contribution from the electronic component (10–3%) of the conductivity is within the sensitivity of the Liang–Wagner technique. A considerable alkali conductivity is observed upon introduction of more than ∼12 mol % Na2O. The true transport number of sodium η Na is as large as unity at [Na2O] ≅ 15 mol %. It is shown that the observed temperature–concentration dependences of the electrical and transport properties are governed by the ratio between the concentrations of polar and nonpolar structural–chemical units of the Na+[BO4/2]–, Na+[O–BO2/2] ⇒ Na+[O–BO2/2], Pb2+1/2[BO4/2]–, Pb2+1/2[O–BO2/2], and [BO3/2] types.

Development of the R.L. Muller model of the microheterogeneous structure of glass and its application for various glass types

The possibility of the application of the R.L. Muller model of the microheterogeneous structure of glass for the description of the nature of the conduction various glass classes, the electric conduction of which is due to the migration of cations, anions and the combined migration of cations and electrons, has been considered. It was shown that the appearance and the subsequent increase in the ionic conduction can be explained using the concentration variation of the blocking extent function (γ), which is calculated based on the analysis of the ratio of the concentration of nonpolar and polar structural fragments—structural-chemical units in the bulk of glass. On the whole, the methodology of the calculation of the concentration γ values for various glass systems coincides, except for some features in halogen-containing systems that required additional specifications.

The effect of the protonic component of conduction on the electrical properties of oxide glass

A short review of works devoted to studying the effect of hydrogen-containing fragments of the structure (mainly H2O and OH−-groups) on the physicochemical (mainly electrical) properties of oxide glass has been presented. It was noted that the conduction of alkali-free oxide glass is due to the migration of protons. When introducing alkali metal oxides in their composition in the region of low Me2O concentrations, the electric current transport is due to the combined migration of protons and alkali metal ions; the conduction due to the migration of exclusively alkali ions is observed at concentrations of alkali metal ion oxides higher than 20 mol %. It was noted that in oxide glass containing ions of alkaline earth metals the conduction is also due to the migration of impurity protons. No participation of ions of alkaline earth metals in the electricity transport was observed.

Temperature-concentration dependence of the electrical conductivity of glasses in the Zn(PO3)2-NaF system

Temperature-concentration dependence of the electrical conductivity in glasses of the Zn(PO3)2-NaF system was studied and compared with similar dependences for glasses of other systems. The extremal dependences log σ = f([Na+]) and {ie937-1} are interpreted from the standpoint of a macroscopically inhomogeneous structure of the glasses under study.

Nature of current carriers and electric properties of glasses in xAg2O · (0.2 − x)Tl2O · 0.8B2O3 system

The effect of substituting thallium oxide with silver oxide on some physicochemical properties of glasses in the xAg2O-(0.2 − x)Tl2O · 0.8B2O3 system at x = 0, 0.04, 0.08, 0.12, 0.16, and 0.20 has been investigated. It has been established that, upon this substitution the concentration dependences of the glasses conductivity activation energy and electroconductivity are of an extreme-type character, whereas similar dependences of other properties (microhardness, glass formation temperature, and density) are nearly linear. The study of the nature of current carriers and transport numbers in accordance with the Hittorf technique has shown that silver ions and protons (resulting from dissociation of water always present in glasses) participate in the transport of electric current. As was concluded based on the experimental data, thallium ions do not participate in electricity transport. The rule of additivity of electroconductivity is not valid for glasses in the Ag2O-Tl2O-B2O3 system.