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For potential applications in electronic components and sensor elements, lithium-niobium-titanium oxide ceramics are prepared by a solid-state reaction method. Two different weight percentages (2 and 5 %) of ZnO as a functional additive are added before the mechanical milling step in two separate procedures and changes in microstructure, and electrical properties are investigated. Analysis of microstructure by scanning electron microscopy showed the morphology of the synthesized particles in the form of plates and rods, which corresponds to the desired microstructure of the M-phase class of lithium-niobium-titanium oxide ceramic materials. The addition of ZnO creates a trend of increasing the total bulk density. X-ray diffraction analysis by Rietveld refinement and deconvolution of the Raman spectra by Lorentzian line shape fitting enabled the characterization of the crystal structure and vibration properties. In the frequency range from 100 Hz to 10 MHz, the analysis of the obtained impedance spectra at room temperature shows that the tested samples have non-Debye dielectric relaxation. Furthermore, the appearance of one semicircle on the Cole-Cole plots indicates the dominant influence of grain boundary effects on the electrical behavior of the studied ceramics in the measurement frequency range. Finally, a room temperature study of the humidity sensing properties showed that the 2% ZnO sample had a better linear impedance change response over a wide range of relative humidity from 15% to 85% at a frequency of 15 kHz. [ABSTRACT FROM AUTHOR]

In this paper we present the results of optical and spectral characteristics of the quasibinary glassy system Bi-As2S3. From the obtained spectra we determined the optical band gap and the level of structural disorder for different doping atoms content. The decrease of the optical gap with increase on Bi atoms content was discussed in terms of chemical composition and arrangement of structural units, using the Raman spectroscopy results. The Wemple-DiDomenico model was used to describe the refractive index behavior and correlations between linear and nonlinear optical quantities of investigated chalcogenides, yielding significant parameters for the structural analysis. Having obtained high values of nonlinear refractive index, potential applications of these materials in telecommunication systems are discussed. [ABSTRACT FROM AUTHOR]

Thermal properties of glasses from the system Agx(As40S30Se30)100-x for x = 0, 0.5, 1, 3, and 5 at.% were investigated by differential scanning calorimetry. The DSC curves were obtained under non-isothermal conditions which allowed determination of the glass transition temperature Tg (onset temperature), crystallization temperature Tp (corresponding to the crystallization peak maximum), melting temperature Tm, crystallization enthalpy Hc, and melting enthalpy Hm. The DSC curves obtained at the same heating rate were analyzed in order to study the variation of glass transition temperature with Ag concentration. Observed Tg shift toward higher values, with increase in the heating rate, is in agreement with the Lasocka equation. Samples with 3 at.% and 5 at.% Ag were further thermally treated at different heating rates with the aim of analyzing kinetic processes of crystallization. The Moynihan and Kissinger models were used to calculate the activation energy of glass transition and activation energy of crystallization. For the samples that showed the crystallization processes an assessment of the thermal stability was done based on different criteria. [ABSTRACT FROM AUTHOR]

This paper presents and discusses the results of the instrumented indentation test of the samples of the system Bix(As2S3)100-x, x = 1:5, 3, 5, and 7 at.%. Measurements of mechanical parameters were performed using a Fischerscope HM2000 S nanoindentation device. The experimental data obtained by measuring the microhardness parameters were used to determine some other mechanical quantities that are important for the characterization of the examined materials in terms of their potential applications. For the first three compositions, the results indicated an increase in the microhardness with the increase in the content of doping atoms, which can be interpreted as an enhancement of the strength and stiffness of the structural network. The lower value of microhardness of the sample with the maximum content of Bi can BE associated with the specific structure of this composition. The pronounced indentation size effect was also detected on the indentation curve in the range of smaller loads. According to the model of elastic-plastic deformation, applied for the description of indentation size effect measured for the investigated chalcogenides, the largest value of the elastic recovery was observed for the sample Bi7(As2S3)93. The calculated values of the elasticity modulus show that the glass with x = 5 at.% Bi is characterized with the highest atomic packing density. [ABSTRACT FROM AUTHOR]