Electrical, dielectric, and optical properties of Sb2O3–Li2O–MoO3 glasses

International audienceTemperature and frequency dependencies of DC and AC conductivities, dielectric response, static permittivity, optical absorption edge, infrared absorption spectrum, density, and temperatures of glass transition and crystallization for lithium molybdenum–antimonite glasses, (80 − x)Sb2O3–20Li2O–xMoO3, where x = 0–40, are measured and discussed. The DC conductivity increases with increasing concentration of MoO3. At 150 °C, it ranges from 5 × 10− 11 S/m up to 3 × 10− 8 S/m. Polaron hopping between Mo5 + and Mo6 + ions contributes, probably, to the DC conductivity. Ionic conductivity by Li+ ions is also present. The conduction activation energy monotonously decreases from 1.15 eV, at x = 5, down to 0.91 eV, at x = 40. In all glasses with x > 0, the conduction activation energy is close to a half of the indirect allowed optical gap. The pre-exponential factor, σ0, goes through a sharp maximum close to the composition (x = 20) with both the highest glass transition temperature and the largest thermal stability range. The frequency dependence of the AC conductivity is composed of three components — the DC conductivity and two AC components. For x = 35 and 40, the activation energy of electrical relaxation is equal to 0.954 ± 0.008 eV and the pre-exponential factor of relaxation times is equal to (4 ± 1) 10− 14 s. The static relative permittivity ranges from 17.4 to 23.0. Strong extrinsic absorption bands in infrared region originate from hydroxyl ions, CO2 impurities, and silicon–oxygen vibrations. The UV–visible indirect allowed absorption edge shifts from 2.6 eV to 2.1 eV with increasing MoO3 content. With increasing MoO3 content the glasses darken, from a light yellow color, at x = 0, to a deep brown color, at x = 40

The Relationship Between Mechanical and Electrical Properties During Vulcanisation of SBR Based Rubber

The aim of this paper is description of vulcanization process by monitoring of selected electrical and mechanical parameters. The experiments have shown that the vulcanization process can be qualitatively and quantitatively evaluated on the basis of measurements of mechanical (standard procedure in rubber industry) and also electrical parameters. The results obtained for model system SBR rubber mixture under conditions of linear heating are presented also

Electrical and dielectric properties of Sb2O3-V2O5-K2O glasses

International audienceElectric measurements, including temperature dependencies of direct electrical conductivity and temperature dependencies of complex electrical modulus, have been implemented using Sb2O3-V2O5-K2O glass samples. These glasses absorb ambient humidity but their resistance to water attack depends on composition. The significant decrease of conductivity up to 100 °C can arise from water desorption. Cycling measurements of direct electrical conductivity versus temperature were also implemented. They show that the 30Sb2O3-30V2O5-40K2O and 70Sb2O3-30K2O glasses are irreversibly damaged with the formation of the hydrated layer. In addition, it was observed that the evolution of DC conductivity is ruled by Arrhenius relation, while activation energy decreases as Sb2O3 concentration increases

Electrical and dielectric properties of MnF2-ZnF2-NaPO3 glasses

International audienceDirect electrical conductivity and dependencies of complex electrical modulus vs. temperature and frequency have been measured on glasses from the MnF2-ZnF2-NaPO3 system. These glasses are sensitive to atmospheric humidity and as a consequence, the electrical conductivity increases up to temperature of 50 °C. A hydrated layer is created by the effect of water and leads to the significant increase of the electrical conductivity in the case of 0MnF2-20ZnF2-80NaPO3 glass. This behavior is governed by Arrhenius relation where the values of activation energy are increasing and values of the electrical conductivity are decreasing with the amount of MnF2. Dielectric measurements show that a heterogeneous phase is formed in the bulk of glasses. This may be seen when plotting complex electrical modulus in the complex plane. The records made by the light microscope confirmed the occurrence of the other phase in the bulk of glasses

Electrical, dielectric and optical properties of Sb2O3-PbCl2-MoO3 glasses

International audienceElectrical, dielectric, and optical properties of lead molybdenum antimonoxychloride glasses, (90 − x)Sb2O3-10PbCl2-xMoO3 (x ∈ {10,15,...35} mol%), are reported and discussed. DC conductivity is measured in the temperature range from − 50 °C up to 160 °C. At higher temperatures, temperature dependences of the dc conductivity are Arrhenius-like with conduction activation energies equal to 1.00 ± 0.06 eV. With increasing concentration of MoO3 the dc conductivity increases. At lower temperatures, the activation energy slightly decreases; this decrease is more pronounced at higher concentration of MoO3. It is probable that electron hopping between Mo5 + and Mo6 + contributes to the dc conductivity, at low temperature. Frequency dependences (100 Hz to 100 kHz) of ac conductivity and relative permittivity are measured at a constant temperature in the range (20-200 °C). Modular analysis gives static relative permittivity ranging from 20.2 up to 24. Infrared spectra and UV-VIS spectra are measured. Strong extrinsic absorption bands in infrared region originate from hydroxyl groups, CO2 and Si-O vibrations. The slope of UV-VIS absorption edge edge decreases and the optical gap shifts to longer wavelengths with increasing MoO3 content

New Dynamic Method for Examination of Elastic Properties of Thin Wire Samples

Classical reverse pendulums are currently used for measuring the gravity acceleration g, or – when pendulums bodies are connected by the spring – for demonstration of composition of parallel vibrations. In this paper we present the reversed pendulums in „non-traditional” position – as a device for measuring of elastic modulus of wire samples. The connection is realized by the measured wire sample with the circle shape

Investigation of Physical Properties of Polymer Composites Filled with Sheep Wool

Sheep farmers are currently facing an oversupply of wool and a lack of willing buyers. Due to low prices, sheep wool is often either dumped, burned, or sent to landfills, which are unsustainable and environmentally unfriendly practices. One potential solution is the utilization of sheep wool fibers in polymer composites. This paper focuses on the study of mechanical vibration damping properties, sound absorption, light transmission, electrical conductivity of epoxy (EP), polyurethane (PU), and polyester (PES) resins, each filled with three different concentrations of sheep wool (i.e., 0%, 3%, and 5% by weight). It can be concluded that the sheep wool content in the polymer composites significantly influenced their physical properties. The impact of light transmission through the tested sheep wool fiber-filled polymer composites on the quality of daylight in a reference room was also mathematically simulated using Wdls 5.0 software

A monitoring of the kinetics thermally degradation selected rubber by electrical methods

The work presents the possibilities of diagnostics of irreversible chemical reaction - thermal degradation in case of industry prepared rubber mixture based on styrene - butadiene (SBR) using measurements of selected physical parameters. Our attention was focused on the measurement of electrical parameters (electrical conductivity). Procedure of the measurement of electrical properties was applied at the constant temperatures from the range 150 °C to 200 °C. The determination of electrical properties by means of the measurements of time dependencies of alternate conductivity (σAC=σ(t)), were performed in frequency range 20Hz - 100kHz. It is possible describe significant constants of the kinetics of degradation reaction (reaction rate coefficient) by the solution of differential equations and by mathematical approximation. The constants are exponentially dependent on the temperature of thermal degradation. In addition the approximation allows describe the thermal degradation in the temperature range outside of the monitoring interval. © 2019 Author(s).Slovak Science Foundation [VEGA 1/0235/18]; Research & Development Operational Programme - ERDF [ITMS: 26220120048

Electrical and dielectric properties of glass system NaPO3-KHSO4

International audienceGlass samples have been prepared in the NaPO3-KHSO4 binary system with the classical melting, casting and annealing steps. Electrical and dielectrical properties of glass samples were studied. Measurements of DC and AC conductivity and complex electrical permittivity of xNaPO3-(100 − x)KHSO4 glass system were carried out at temperatures ranging from room temperature to temperature located 15 °C below glass transition temperature Tg. Results showed that changes of NaPO3 concentration considerably affect values of observed parameters. DC conductivity of glass increases as NaPO3 concentration grows until concentration x = 60. However, beyond this value a sharp decrease of DC conductivity was observed. In addition relaxation times showed abrupt changes at concentration x = 60, corresponding to the lowest relaxation times at the temperature 90 °C

Properties of Sn-Ag-Cu Solder Joints Prepared by Induction Heating

In the present work, one near-eutectic and three hypoeutectic Sn-Ag-Cu alloys have been employed for soldering by induction heating. The alloys were produced by induction melting of high purity Ag, Cu, and Sn lumps. The melting behavior of the alloys was investigated by differential scanning calorimetry. The solder alloys were subsequently applied for soldering by conventional hot-plate heating as well as induction heating and both soldering times and peak temperatures were recorded during soldering. Solder joints of two copper sheets were produced. The electrical resistance, tensile strength, and microstructure were analyzed on each soldered joint. The results indicate that the physical and mechanical properties of solder joints are determined by their chemical composition and soldering technology. Induction soldered joints not only have a slightly higher electrical resistivity but also higher mechanical strength, except of the 0.3 wt.% Ag hypoeutectic solder. The highest increase in ultimate tensile strength (28%) was observed for induction soldered joints with 1 wt.% Ag hypoeutectic solder. This effect is ascribed to the homogenous distribution of the intermetallic compounds within the eutectic in the alloy microstructure. The homogenous distribution is aided by rotation of liquid solder due to eddy currents and high-frequency magnetic field generated during induction heating