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 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, 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

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

Preparation and characterizations of glasses in the TeO2–Ga2O3–M2O (M═Li, Na, K) systems

International audienceGlasses in the TeO2–Ga2O3–M2O (M═Li, Na, or K) systems were synthesized by a melt‐quenching technique. The glass forming areas were delimited for each system. Systematic analyses were performed on two series of samples—the first one with a constant TeO2/Ga2O3 ratio of 85/15, that is, [(TeO2)0.85(Ga2O3)0.15]100−x[M2O]x with 0 ≤ x ≤ 25 (with a step of 5 mol%), the second one with a constant alkaline oxide concentration of 10 mol%, that is, [TeO2]90‐y[Ga2O3]y[M2O]10 with 5 ≤ y ≤ 15 (with step of 2.5 mol%). The values of the glass transition temperature, density, and optical transmission parameters (the positions of short‐ and long‐wavelength absorption edge and the maximum transmittance value) were determined. The changes in these parameters were studied for varying glass compositions. In addition, the values of refractive index were measured at various wavelengths across the whole transparency region reaching from the visible up to the mid‐infrared range

Developing in vivo biophysics by fishing for single molecules

10.1016/j.ydbio.2010.08.004Developmental Biology34711-8DEBI