16 research outputs found
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
Testing wireless electro-osmosis used for dehumidification in civil engineering
Paper presents and explains the differences between non wireless and wireless electro-osmosis. Based on information provided by companies that use electromagnetic fields of different frequencies, the device was designed, built and tested in the basement of a historic building and in the laboratory. The experiments confirmed (in all evaluated tests) that the wireless electro-osmosis does not affect the amount of water in porous materials
Electrical and Dielectric Properties of Sb2O3-PbCl2-AgCl Glass System
International audienceElectrical and dielectric properties of ternary glasses in the Sb2O3-PbCl2-AgCl system were investigated across a broad temperature and frequency range. The studied glass system is interesting since it possesses a high ionic conductivity. The (Sb2O3)(x)-(PbCl2)(100 -y)(-)(x)-(AgCl)(y) glasses were prepared by melt-quenching method from high purity components. Different batches of these glasses were investigated with varying molar content of both Sb2O3 (45 <= x <= 70 mol %) and AgCl (5 <= y <= 25 mol %). The colour of the prepared chloro-antimonite glasses varies between yellow and brown. The glass transition temperature (T-g) decreases with increasing AgCl concentrations. DC and AC electrical conductivities and complex electrical modulus were measured across a temperature range from room temperature up to 200 degrees C and across a frequency range between 0.2 and 10(5) Hz. The dependence of DC conductivity on temperature follows the so-called Arrhenius-like equation. The DC conductivity at constant temperature significantly increases with increasing AgCl or PbCl2 content. It was found that the activation energy of conduction process decreases with the substitution of PbCl2 by AgCl from 1 eV down to 0.56 eV for (Sb2O3)(50)-(PbCl2)(45)-(AgCl)(5) and (Sb2O3)(50)-(PbCl2)(25)-(AgCl)(25), respectively. The influence of the composition on the AC conductivity of the investigated glasses is also discussed
Temperature microsensor/microactuator based on magnetic microwire for MEMS applications
The aim of this paper has been the development of a new type of temperature microsensor/microactuator working on the principle of the thermo-elastic (TE) deformation of multilayer magnetic microwire consisting of a glass-coated CoSiB metallic core and an electroplated CoNi external shell. The application of an electrical current along the microwire in the range 20-35 mA results in the TE mechanical bending of fixed sample, which is recorded. That mechanical deformation is interpreted to be a consequence of the resulting Joule heating, and its amplitude is directly proportional to the applied dc current in the mentioned range. Moreover, the direct proportionality between TE deformation and the resulting increase of temperature was experimentally confirmed. In this way, the new type of temperature microsensor/microactuator working on the principle of TE deformation has been developed. This opens new technological application of microwires as temperature microsensors and temperature-driven microactuators for micro-electro-mechanical system devices
Influence of NaI Additions on the Electrical, Dielectric, and Transport Properties in the GeS2-Ga2S3-NaI Glass System
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Local atomic structure and electrical properties of (x=0, 5, 10, and 15) glasses doped with Ho
Measurements of ac and dc conductivities, complex electrical modulus, static permittivity, dielectricrelaxation, and X-ray diffraction of the glassy system Ge20Se80xTex (x = 0, 5, 10, and 15), ‘‘pure’’ anddoped with 1000–2000 wt.-ppm Ho (added as metal or oxide), are presented and discussed. Influenceof crystallization and/or phase separation on these properties is described.Temperature dependences of the dc conductivity are Arrhenius-like; their conduction activation energyincreases (0.73–0.84 eV) and the dc conductivity decreases (1.51068108 S/m, at 60 C) withdecreasing concentration of Te. Doping with Ho3+ ions in a metallic form decreases the conduction activationenergy. Relative static permittivity of glasses ranges from 9.6 to 12.8. The highest values are foundin heavily doped, partly crystallized glasses. The lowest values are found in ‘‘pure’’ glasses with a highcontent of Te. At 1000 wt.-ppm Ho, modular diagrams are almost semicircular, modular spectra areDebye-like, and their shape is independent on temperature. At 2000 wt.-ppm Ho, two relaxation processesappear and the shape of both modular diagrams and modular spectra depend on temperature. Apartial crystallization takes place in these glasses.For heavily doped glasses (1500 and 2000 wt.-ppm Ho), XRD experiments, using high-energy photons,show distinct Bragg peaks stemming from a tiny fraction (about 0.25%) of crystalline phases. Crystallinecomponent is rather homogeneously distributed within the sample. Changing level of Ho doping affectsthe short-distance arrangement in glasses. A higher level of Ho doping implies shortening of the interatomicdistances, higher mean atomic density, and higher coordination numbers what suggests betteratomic packing