Electrical Conductivity Of Glasses Research Articles

Electric Conductivity of Glasses in the MgO–V2O5–P2O5 System

Electric Conductivity of Glasses in the MgO–V2O5–P2O5 System

Conductivity and morphological studies on iron borosilicate glasses

A set of glass samples of nominal composition xFe2O3.(43-x)B2O3.25SiO2.30Na2O. 2Al2O3, (x ≤ 40 mol%) was prepared via an ordinary melt quenching route. The variation of structural and electrical characteristics of the prepared samples have been studied. Electrical conduction in glasses that contain Fe2O3 (≤ 20 mol%) is considered to be ionic. Otherwise, the polaronic conduction is dominant in glasses of higher Fe2O3 concentrations (>20 mol%). Energy dispersive x-ray analysis of glass containing 5 mol% Fe2O3 showed that only one type of modifying iron ions Fe3+ present in their octahedral coordination. Besides, glasses containing higher Fe2O3 content reveal the presence of a mixture of both ferrous and ferric ions (Fe2+ & Fe3+). A fraction of both tetrahedral (BO4 and FeO4) units and BO3 groups are determined from Fourier transform infra-red spectroscopic analysis (FTIR). Increasing the fraction of tetrahedral units and decreasing BO3 are considered as the main reasons in conductivity enhancements.

Electrical conductivity and viscosity of phosphate glasses and melts

Phosphate glasses are of great interest for basic research and for special applications in various fields as technical and optical glasses. Metaphosphate compositions with PO4-chain structure are mostly used. The cations have a significant effect on the properties of the glasses and melts. This was studied in more details. High purity metaphosphate glasses, Mn(PO3)n with M = Na+, K+, Zn2+, Mg2+, Ca2+, Sr2+, Ba2+, Al3+ and Fe3+, were prepared and the optical and thermal properties were measured with different methods. The electrical conductivity of glasses and melts is the property of great practical importance. It was determined by impedance spectroscopy in a wide temperature range from 300 to 1250 °C in frequency range of 0.1 Hz to 6 MHz. The electrical conductivity of alkaline earth phosphate glasses and melts increases with increasing ion radius of the cation. NaPO3 and KPO3 glasses and melts have much higher conductivity. Viscosity measurements were carried out from transformation temperature, Tg, to the melt. The measured data were fitted and the activation energies of the conductivity and viscosity were calculated. Simple exponential behavior was found at temperatures below Tg, but above Tg only in very narrow temperature range. The relation between conductivity and viscosity was considered.

Effect of gamma irradiation on the density, glass transition temperature and electrical conductivity of lithium borosilicate glasses with alumina addition

Lithium borosilicate glasses (LBS) with alumina addition have been synthesized. The effect of gamma irradiation on the density, glass transition temperature (Tg) and electrical conductivity of these glasses has been studied. It has been observed that, the density and (Tg) of lithium borosilicate glasses decreases and electrical conductivity increases with addition of alumina. The formation of AlO4 tetrahedra expands the lattice which explains the decrease in density and Tg. The increase in electrical conductivity has been attributed to the increase in (NBOs).With gamma irradiation the density and Tg increase due to formation BO4 tetrahedra at the cost of AlO4 resulting into compact and dense glass network. The electrical conductivity decreases after irradiation due to reduction in the number of NBOs and the formation of more closed network. There is a very good correlation among the density, Tg, FTIR and electrical conductivity for the glasses studied in the present work.

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.

Structure and electrical conductivity of glasses in the Na2O-Na2SO4-P2O5 system

The temperature-concentration dependence of the electrical conductivity of glasses in the Na2SO4-NaPO3 and Na2O-P2O5 systems has been investigated. Based on the obtained experimental data (IR spectra, density, microhardness, sound velocity, and paper chromatography), it has been demonstrated that SO42− ions form terminal groups through the incorporation into polyphosphate fragments of the structure of glasses in the Na2SO4-NaPO3 system. An increase in the electrical conductivity of glasses in this system by a factor of ∼1000 (as compared to NaPO3) at 25°C and a decrease in the activation energy for electrical conduction from 1.40 to 1.10 eV have been interpreted from the viewpoint of the decrease in the dissociation energy Ed of polar sulfate phosphate structural chemical fragments formed in the glass bulk upon introduction into sodium metaphosphate Na2SO4. This leads to an increase in the number of dissociated sodium ions, which are charge carriers, and to a decrease in the energy (Ea) of their activation shift in the sublattice formed by sulfate phosphate fragments of the structure.

Glass formation and electrical conductivity of glasses in the Na2Se-P2Se5 system in a wide temperature range

The glass formation region in the Na2Se-P2Se5 system and the temperature-concentration dependences of the electrical conductivity of glasses have been investigated over a wide range of temperatures. The densities and glass transition temperatures T g of glasses have been determined. A comparison of the electrical conductivity of glasses in the Na2Se-P2Se5 and Na2O-P2O5 systems has demonstrated that the conductivity of selenium-containing glasses (at 25°C) is approximately three orders of magnitude higher than the electrical conductivity of oxide glasses. The assumption has been made that an increase in the electrical conductivity of glasses with selenium is caused by the increase in the degree of dissociation of Na+[Se−PSe3/2] polar structural chemical units and the higher mobility of sodium ions in the oxygen-free matrix.

Electrical conductivity and the nature of charge carriers in glasses of the Tl2O-B2O3 system

The concentration dependence of the electrical conductivity of glasses in the Tl2O-B2O3 system is studied. The nature of charge carriers in this system is experimentally investigated for the first time. It is demonstrated using the Hittorf, Tubandt, and Hebb-Liang-Wagner techniques and the Faraday law that neither Tl+ ions nor electrons are involved in the electricity transport. The verification of the Faraday law does not reveal the presence of thallium in the amalgam of the cathode or a change in the sample weight after electrolysis, to within the experimental error. This allows one to make the inference that protons can be charge carriers in glasses of the Tl2O-B2O3 system. It is shown using extended X-ray absorption fine structure (EXAFS) spectroscopy that Tl3+ ions and thallium Tl0 reduced to the metallic state are absent in the structure of the glasses under investigation. This means that thallium in glasses of the Tl2O-B2O3 system occurs only in the form of Tl+ ions. The analysis of the IR spectroscopic data leads to only a qualitative conclusion that the water content in the glasses insignificantly increases with an increase in the thallium oxide content. An increase in the electrical conductivity of glasses in the Tl2O-B2O3 system with an increase in the thallium oxide content is explained by the increase in the number of protons formed upon dissociation of H+[BO4/2]− structural-chemical units, because their concentration increases with increasing Tl2O content. In the structure of boron oxide, impurity hydrogen enters predominantly into the composition of H+[O2/2BO−] structural-chemical units, for which the dissociation energy is higher than that for the H+[BO4/2]− structural-chemical units. The increase in the concentration of H+[BO4/2]− structural-chemical units is accompanied by the increase in the number of dissociated protons, which are charge carriers in glasses of the Tl2O-B2O3 system.

Dielectric universal law of lead silicate glasses doped with neodymium oxide

Dielectric spectroscopy can, nowadays, cover a very broad frequency range by using a tuned combination of different measurement instrumentation. This technique can provide very useful information concerning the electrical conductivity of glasses used frequently as insulators, and on the possibility of new applications in a large frequency range. In this work we present the dielectric response of lead silicate glasses doped with neodymium oxide, in the frequency range 100mHz–100kHz, and temperature between 300K and 600K. The dielectric behavior follows a power law, ε′(ω)=Bωn-1+ε∞, which is a consequence of the Curie-von Schweidler regime in the time domain. This behavior is frequently applicable to different structural forms, types of chemical bounds and geometric configurations. The values obtained for the exponent n, show that a weak dependence of the permittivity on frequency is observed. The variations with the concentration of the doping oxide are not significant. Nevertheless, the B parameter suffers a variation with concentration, which confirms the cluster formation at a critical concentration.

Electric conductivity of glasses in the system Na2O/CaO/SiO2/Fe2O3

Abstract The addition of polyvalent transition metal ions to the usually insulating traditional soda-lime–silica glasses can lead to semiconducting properties. We report on synthesis of glasses and glass-ceramics in a soda-lime-silicate based system containing Fe2O3 in the concentration range from 5 to 30 mol%. Two sub-systems were considered, in one of them the ratio [Na2O]/[Fe2O3] was varied while in the other one, the ratio [SiO2]/[Fe2O3] was changed. The phase composition of the synthesized products was characterized by X-ray diffraction and energy dispersive X-ray analysis, while the electrical properties were studied by impedance spectroscopy. Partially crystallized non-reduced samples are semiconducting even at room temperature while the glassy samples (both reduced and non-reduced) exhibit semiconducting properties at temperatures equal or larger than 100 °C. An attempt is done to predict the physical approximation explaining the conduction process in the glasses.

Hierarchical percolation and electrical conduction of glasses in the 50WO3-(50 − x)P2O5-xNa2O system

The validity of the proposed concept of hierarchical percolation is demonstrated using glasses in the WO3-P2O5-Na2O system as an example. The dependence of the electrical conductivity σ = σ0(ξ − ξcrit)μ (where ξ is the percolation parameter) with an exponent μ ≃ 1.4 close to the exponent theoretically predicted for two-dimensional percolation is obtained for the first time. This confirms our hypotheses regarding the two-dimensional percolation nature of electrical conduction over the surface of a phosphate cluster after the percolation threshold is overcome.

Vitreous solid state electrolytes in the system of RNO 3–Zn(NO 3) 2–KHSO 4–P 2O 5

The structure and electric conductivity of glasses in the system RNO 3–Zn(NO 3) 2–KHSO 4–P 2O 5 ( R = Na, K) obtained at different temperatures were investigated by IR and impedance spectroscopy. Glasses fused at 250–350 °C demonstrated an increase of their ionic conductivity in 10 3 times in comparison with the same compositions fused at 550 °C. The influence of the chemical composition on the structure and properties of the obtained glasses was analyzed. It is proposed that the high ionic conductivity of glasses obtained at low temperatures is related to the incorporation of the nitrate ions between long (PO 3) n chains, similar to the iodide ions; this resulted in a maximal coordination of the local conduction space for the cation associated with a disordered glass network.

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.

Effect of nanocrystallization on electrical conductivity of glasses and composites of the AgI–Ag 2O–B 2O 3 system

Amorphous and glassy–crystalline samples of the AgI–Ag 2O–B 2O 3 system with high content of AgI were prepared. It was shown that annealing of initially amorphous samples (with AgI content not higher than 60 mol%) leads to formation of crystalline grains of β-and γ-AgI and to a conductivity increase to 1.1·10 − 2 S cm − 1 at 20 °C (for AgI content of 55 mol%). The conductivity enhancement was attributed to interfacial regions surrounding crystalline grains. As-received samples with higher contents of AgI (≥ 75 mol% AgI) have high concentration of crystalline grains, mainly of AgI. The temperature dependence of conductivity undergoes step-like changes (close to 150 °C on heating and close to 120 °C on cooling). These changes are a consequence of the β-α-AgI phase transitions taking place in the crystallites.

Electrical conductivity of glasses in the Ag-As-Se-Te system

The electrical conductivity of glasses in the Ag-As-Te-Se system is investigated by impedance spectroscopy for compositions lying along two joins, namely, Ag0.2-As0.4-(Tex-Se1 − x)0.4 and (Ag2Se)0.2-[(As2Te3)x-(As2Se3)1 − x]0.8. The transport numbers are measured using the Wagner method. It is found that, in the glasses containing silver in large amounts, the electron-hole conduction is predominantly provided by electrons rather than by holes, as is usually observed in chalcogenide glasses.

Electrical conductivity and relaxation frequency of lithium borosilicate glasses

Electrical conductivity of glasses from the system 0.40Li 2O·0.60( xB 2O 3(1− x)Si 2O 4) (0≤ x≤1) were measured by impedance spectroscopy. The influence of the substitution of the first glass former by the second in electrical conductivity and in the parameters of the Arrhenius expression, i.e., activation energy and pre-exponential factor, is discussed. The electrical conductivity increases from the silica to the boron oxide region, with an anomaly at x=0.3 but with no evidence of a mixed glass-former effect. The relaxation frequency, which is an intrinsic characteristic of each glass sample and is independent of geometrical parameters, was also deduced from impedance diagrams and are also presented for all compositions.

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.

Effect of Fluorine Ion on the Electrical Properties of Glasses in the Na2O–P2O5 System

The temperature–concentration dependence of the electrical conductivity of glasses in the NaPO3–NaF system has been investigated. The regularities revealed are interpreted from the standpoint of the structural microinhomogeneity of glasses, which is due to the formation of polar structural units of the Na+[O–POO2/2], Na2+[O–2POO1/2], Na+[F–POO2/2], and Na+F– types. It is shown that the concentration dependence of the electrical conductivity is governed by the ratio between the concentrations of these structural units.

Proton Conduction in Porous Silica Glasses with High Water Content

Silica glasses with high surface area were prepared by the sol−gel method, the electrical conductivity of which was measured as a function of the content of adsorbed water. The glasses obtained by heating at 400−800 °C had specific surface areas of 700−900 m2/g glass and exhibited room-temperature conductivities of 10-6−10-3 S/cm by absorbing the water in pores. The activation energy for conduction linearly decreased with increasing logarithm of the product of proton and water concentration. On the other hand, the increase in conductivity was represented to be proportional to the logarithm of water concentration. Electrical conduction in glasses containing a large amount of water is related to the dissociation of protons from the SiOH bonds and the proton hopping through water molecules in pores.

Raw materials from the Kursk Magnetic Anomaly region: The basis of glass materials for electrical engineering

The paper sums up a study into the electrical conductivity of glasses and glass ceramics fabricated from nonscarce raw materials, mining and ore-dressing wastes available in the Kursk Magnetic Anomaly (KMA) region. Consideration is given to SiO2−Al2O3−Fe x O y −(Ca,Mg)O−(Na,K)2O glasses which are close to high-alkali glasses in melting and pouring characteristics and to alkali-free glasses in resistivity.