Research Interests:
The vitreous system GeS2–Ga2S3 can incorporate a large amount of alkali salts, for example NaI, and such materials have a potential to be used as solid electrolytes for all-solid-state batteries. The present work focuses on the effects of... more
The vitreous system GeS2–Ga2S3 can incorporate a large amount of alkali salts, for example NaI, and such materials have a potential to be used as solid electrolytes for all-solid-state batteries. The present work focuses on the effects of NaI addition in the (GeS2)x(Ga2S3)100 –x glass matrix, where x = 65, 72, 80, and 88. AC and DC electrical and dielectric properties were measured in the temperature range from 20 up to 200°C and in the frequency range 1 Hz–100 kHz, in air, at different temperatures by steps of 1°C. The values of electrical conductivity significantly increase with increasing of NaI content. The DC conductivity values 2.5 × 10–4 S m–1 at room temperature were detected for glasses with 25 and 30 mol % of NaI in (GeS2)72(Ga2S3)28 and with 30 mol % NaI in (GeS2)65(Ga2S3)35 matrices. Samples with NaI concentration higher than 20 mol % show a poor stability against moisture. In order to improve their stability the glass composition was modified by addition of 2.5 mol % P2S5 in the system. The activation energy values slightly decrease with NaI content. The GeS2/Ga2S3 ratio and P2S5 addition to the glass matrix have low effect on transport properties. The DC conductivity, electrical relaxation, and depolarization mechanisms are similar. Electrical charge transfer is connected with hopping of Na+ ions or reorientation of dipoles containing these ions.
Research Interests:
ABSTRACT The paper is devoted to the study of thermal, as well as mechanical properties of polyurethane samples (PU) filled by carbon black (CB), graphite (G) and MWCNT(CNT). Thermal conductivity k(W.m-1.K-1), specific heat capacity... more
ABSTRACT The paper is devoted to the study of thermal, as well as mechanical properties of polyurethane samples (PU) filled by carbon black (CB), graphite (G) and MWCNT(CNT). Thermal conductivity k(W.m-1.K-1), specific heat capacity cp(J.kg-1.K-1) and thermal diffusivity a(mm2.s-1) were measured by the impulse method. An increase of all the above mentioned thermal parameters after addition of fillers under investigation was observed. The dc electrical conductivity drastically increases from PUPU+CBPU+GPU+CNT.
Research Interests:
Correlation between local values of dielectric permittivity and electric potential in axially symmetric dielectric medium located into a constant external electric field was analyzed perpendicularly to the axis of symmetry. The simple... more
Correlation between local values of dielectric permittivity and electric potential in axially symmetric dielectric medium located into a constant external electric field was analyzed perpendicularly to the axis of symmetry. The simple experimental method for identification of dielectric profile of materials with mentioned symmetry was suggested on the basis of this correlation. Then the qualitative assessment of the technological texture of a ceramic blank designed for the production of very high voltage (VHV) insulators was done. Measured voltage differences on the surface of sample of the ceramic blank placed between two electrodes and connected to a source of constant electrical voltage was measured. The technological texture was evaluated in the form of a flat map of curves with the same values of mentioned voltage differences.
Research Interests:
ABSTRACT Bulk glasses Ge250Ga17As83S650 were prepared by direct synthesis from high purity (6 N) elements S, Ga, Ge, As and doped by rare earth (RE) elements — Pr, Dy, Nd, Sm or Ho. The DC and AC electrical conductivity were measured, and... more
ABSTRACT Bulk glasses Ge250Ga17As83S650 were prepared by direct synthesis from high purity (6 N) elements S, Ga, Ge, As and doped by rare earth (RE) elements — Pr, Dy, Nd, Sm or Ho. The DC and AC electrical conductivity were measured, and activation energies of relevant conductivity process were obtained from Arrhenius plots of its temperature dependence. The real part of complex permittivity as a function of temperature and frequency was deduced from AC conductivity data. Room temperature optical transmission and low temperature photoluminescence (PL) spectra were further investigated. The major feature in low-temperature PL spectra is the presence of the broad band luminescence of the base glass and relatively sharp 4f–4f radiative transitions due to the presence of RE3+ ions. When the broad band luminescence spectrally overlaps with 4f–4f transitions of RE3+ ions we can, in some cases, also observe the direct evidence of the energy transfer between the host glass and respective RE dopants which is manifested by the re-absorption of the base glass luminescence due to 4f–4f up-transitions.
Research Interests:
Research Interests:
Research Interests:
Research Interests:
The non-linear response of various physical properties of glasses on mixing of alkali ions is a well-known anomaly in materials science. In this paper, the mixed alkali effect in antimony oxide based glasses with composition... more
The non-linear response of various physical properties of glasses on mixing of alkali ions is a well-known anomaly in materials science. In this paper, the mixed alkali effect in antimony oxide based glasses with composition 60Sb2O3–20WO3–(20 – x)Li2O–x(M2O), where x = 0, 5, 10, 15, 20 (in mol %) and M = Na or K, is studied. The influence of Na/Li and K/Li ratios on ionic AC and DC conductivities is studied. Temperature dependences of the DC conductivity obey Arrhenius-like relation. The conductivity steeply decreases with increasing Na or K content due to larger ionic radius of Na or K ions compared to that of Li. The relation between composition and local movement of electrical charge was investigated and quantified using the measurement of thermally stimulated depolarization currents. The artificial neural network methods for optimizing experimental parameters used in this paper represent a new approach in comparison with works done on glasses with similar composition. The prepared numerical model could be used for the description of the influence of polarization parameters and the optimization of further measurements oriented on activation energies of ion polarization related to local transport of electrical charge, i.e. Li+ and Na+ ions in our case.
Research Interests:
Electrical 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.... more
Electrical 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 (Tg) 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°C and across a frequency range between 0.2 and 105 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.
Research Interests:
New technologies are using natural fibres in composites materials in the industry. It is still often natural fibres in modern buildings, chemists, airports, sport and automotive. Using for construction pieces and their better properties... more
New technologies are using natural fibres in composites materials in the industry. It is still often natural fibres in modern buildings, chemists, airports, sport and automotive. Using for construction pieces and their better properties than steel or traditional materials. New forward science and technic are recycled or decrease waste. The problem for central Europe is a waste of agricultural, invention relates to an epoxy resin filled with an organo-inorganic filler of natural origin, production especially plants and sheep wool as well as other usable wastes such as old textiles. New applications are in new construction types and industries finding cheaper materials. There is available modern technology for injection moulding granulate polypropylene with filler from sheep wool and plant fibres. For example, to make furniture or building cladding. This could reduce waste production, pollution of nature and emissions in the production of these products from new raw materials. The wor...
Research Interests:
Research Interests:
The paper deals with the modeling of the technological texture of the pressed ceramic materials in the radial and axial direction, which consists in the graphical representation and subsequent analysis of the distribution of the... more
The paper deals with the modeling of the technological texture of the pressed ceramic materials in the radial and axial direction, which consists in the graphical representation and subsequent analysis of the distribution of the electrostatic field potential differences on the surface of the dielectric sample with the diameter d and the thickness h located between the electrodes. In occasion of observing radial texture the electrodes have the cylindrical configuration and in occasion of observing the axial texture in the sample the electrodes have the axial configuration. The theoretical relationship in the paper is derived for the calculation of the voltage values measured at any position between the center electrode and the peripheral electrode, at a constant voltage U applied to the outer and inner electrodes of the dielectric sample of thickness h of the raw ceramic sample material (radial texture). Measurements have demonstrated the suitability of identifying the technological ...
Research Interests:
Research Interests:
The exponential increase of the absorption coefficient near the absorption edge is usually explained by existence of the density-of-states tails. Among the quoted theoretical models which are widely used to explain the manifestations of... more
The exponential increase of the absorption coefficient near the absorption edge is usually explained by existence of the density-of-states tails. Among the quoted theoretical models which are widely used to explain the manifestations of the Urbach rule in semiconductors, are the Sumi–Toyozava and the Dow–Redfield models and ab initio (from begining) theory. Our barrier-cluster-heating model assumes the different creating mechanism of exponential tails. The energy by optical transition is provided to electrons except from photons also from vibration of microregion. It deals about the replenishment of absented photons energy, which is smaller as gap width. Absented energy needed for the transition by light absorption is acumulated in certain microregions of material in the form of vibrational energy. At absorption sufficiently big package of accumulated energy can be used. Energy of emptied microarea is filled by phonons from surrounding of microarea (as result of temperature status of surrounding), resp. p...
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Electrical properties of amorphous Ag0.5(As40S30Se30)99.5 alloy have been investigated using complex impedance spectroscopy at different temperatures in the frequency range from 100 Hz to 1 MHz. Direct current (DC) conductivity data... more
Electrical properties of amorphous Ag0.5(As40S30Se30)99.5 alloy have been investigated using complex impedance spectroscopy at different temperatures in the frequency range from 100 Hz to 1 MHz. Direct current (DC) conductivity data follows Arrhenius behavior, while the nature of frequency dependence of alternating current (AC) conductivity follows Jonscher’s power law. Impedance spectra were analyzed by means of an equivalent-circuit model that revealed the presence of a temperature-dependent electrical relaxation phenomenon of the non-Debye type. Different activation energy values of conduction and of the relaxation process were obtained, suggesting different mechanisms of conduction and relaxation. Dielectric properties were analyzed where the real part (ε′) and imaginary part (ε″) of the dielectric constant were found to decrease with frequency and increase with temperature. The temperature coefficient of dielectric constant (TCP) is evaluated. The analysis of dielectric loss leads to determination of the barrier height Wm which is found to be 0.086 eV.
Research Interests:
The problem of the reconstruction of the historical building surface layers is in material compatibility. The crucial physical properties of the convenient material structureon reconstruction are moisture and temperature induced... more
The problem of the reconstruction of the historical building surface layers is in material compatibility. The crucial physical properties of the convenient material structureon reconstruction are moisture and temperature induced deformations. This paper presents experimental results of the coupled moisture and temperature induced expansionof innovative plaster. Detailed thermodynamic analysis can show the deformation contributions of moisture and temperature respectively.The measurements are performedfor moisture content from the dry state to the saturation water contentand temperature range of 10 - 40°C.
Research Interests:
ABSTRACT Influence of crucibles (Au or Pt) on the structure and optical properties of 60TeO2⋅40PbCl2 and 60TeO2⋅20PbCl2⋅20PbF2 glasses, “pure” and doped with 1000 wt-ppm Pr3+ or Er3+, which are added as metals, chlorides, or oxides, is... more
ABSTRACT Influence of crucibles (Au or Pt) on the structure and optical properties of 60TeO2⋅40PbCl2 and 60TeO2⋅20PbCl2⋅20PbF2 glasses, “pure” and doped with 1000 wt-ppm Pr3+ or Er3+, which are added as metals, chlorides, or oxides, is reported. In glasses prepared in Au crucibles, the absorption edge is shifted to shorter wavelengths and the color of the glass is changed from red or orange to yellowish or dirty white, respectively. In the range of 640-700 nm, five Pr or six Er photoluminescence (PL) peaks are observed. In the range of 200 – 1200 cm-1, Raman scattering (RS) spectrums show 6 (for Pr doping) or 7 (for Er doping) bands. Spectrums are deconvoluted using symmetrical Gaussian functions. Relative intensities of PL and RS peaks depend on the chemical form of dopants and on the material of the crucible. Positions of these bands are almost independent of these conditions. On basis of RS spectrums, short-distance ordering of glasses is discussed. Results are compared with those which we have obtained for 70TeO2⋅30PbCl2 glasses.
Research Interests:
Influence of mixing of homovalent cations on the fast anionic conductivity, static permittivity, and thermal diffusivity is investigated in multicomponent fluorite-structured concentrated solid solutions of alkali earth and rare earth... more
Influence of mixing of homovalent cations on the fast anionic conductivity, static permittivity, and thermal diffusivity is investigated in multicomponent fluorite-structured concentrated solid solutions of alkali earth and rare earth fluorides. Influence of mixing of alkali earth cations on electrical properties of fluoride superionics is studied in Ba0.7 − x Sr x La0.3F2.3 single crystals and Ca0.85 − x Sr
Research Interests:
Anisotropy of electrical and dielectric properties of α- and β-BaB2O4, Ba2Na3(B3O6)2F, LiB3O5, and CsLi(B3O5)2 single crystals is reported and discussed. In these crystals, alkali ions are dominant charge carriers; pre-heating to 300°C... more
Anisotropy of electrical and dielectric properties of α- and β-BaB2O4, Ba2Na3(B3O6)2F, LiB3O5, and CsLi(B3O5)2 single crystals is reported and discussed. In these crystals, alkali ions are dominant charge carriers; pre-heating to 300°C eliminates the humidity, preheating to 500 or 600°C, stabilizes the structure and electrical properties of crystals. Then, both ionic conductivity and dielectric response are determined by movement of
Research Interests:
The dc electrical conductivity of the bulk amorphous GeSb2Te4 material has been investigated. Pure and samples doped by 10 at.% SnSe2 have been measured. The conductivity in the samples has been compared with that of SnSe2 bulk sample.... more
The dc electrical conductivity of the bulk amorphous GeSb2Te4 material has been investigated. Pure and samples doped by 10 at.% SnSe2 have been measured. The conductivity in the samples has been compared with that of SnSe2 bulk sample. The activation energy of the doped sample is 0.165 eV. During heating the conductivity of doped material increases, reaches a maximum and then decreases. The comparison with the pure SnSe2 samples allows to explain this behavior by the release above 148 oC of a small ...
Research Interests:
Research Interests:
The objective of this paper is to evaluate, together with adsorption and desorption processes, moisture and temperature induced deformations of two plasters. The measurements are performed for moisture content from the dry state to the... more
The objective of this paper is to evaluate, together with adsorption and desorption processes, moisture and temperature induced deformations of two plasters. The measurements are performed for moisture content from the dry state to the saturation water content and temperature range of 5 – 60°C. The coupled temperature and moisture induced length differences are measured using LVDT MACRO SENSOR SBP 375040.
Research Interests:
Classical reverse pendulums are currently used for measuring the gravity acceleration g, or – when pendulums bodies are conn ected by the spring – for demonstration of composition of parallel vibrations . In this paper we present the
Research Interests:
Research Interests:
In the paper we present application of artificial neural network (ANN) on relation between glass composition versus optical transmittance of the chosen glass systems of Sb2O3 - PbCl2 and Sb2O3 – PbO – M2O, where M was Na, K and Li,... more
In the paper we present application of artificial neural network (ANN) on relation between glass composition versus optical transmittance of the chosen glass systems of Sb2O3 - PbCl2 and Sb2O3 – PbO – M2O, where M was Na, K and Li, respectively. The excellent prediction ability of special ANN program developed for this study demonstrates the possibility to influence the glass composition to obtain asked optical properties. The measurements of the temperature dependencies of the direct electric conductivity show the strong influence of the concentration of the individual glass compounds of systems Sb2O3 - PbCl2 and Sb2O3 – PbO – M2O (M is Na, K, Li) on their electric and dielectric prop…
Research Interests:
Research Interests:
Correlation between local values of dielectric permittivity and electric potential in axially symmetric dielectric medium located into a constant external electric field was analyzed perpendicularly to the axis of symmetry. The simple... more
Correlation between local values of dielectric permittivity and electric potential in axially symmetric dielectric medium located into a constant external electric field was analyzed perpendicularly to the axis of symmetry. The simple experimental method for identification of dielectric profile of materials with mentioned symmetry was suggested on the basis of this correlation. Then the qualitative assessment of the technological texture of a ceramic blank designed for the production of very high voltage (VHV) insulators was done. Measured voltage differences on the surface of sample of the ceramic blank placed between two electrodes and connected to a source of constant electrical voltage was measured. The technological texture was evaluated in the form of a flat map of curves with the same values of mentioned voltage differences.
Research Interests:
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... more
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 ...
Research Interests:
Research Interests:
Research Interests:
The work presents the possibilities of diagnostics of irreversible chemical reaction – vulcanisation using measurements of electrical parameters (DC conductivity). The experimental material was rubber blend based on styrene - butadiene... more
The work presents the possibilities of diagnostics of irreversible chemical reaction – vulcanisation using measurements of electrical parameters (DC conductivity). The experimental material was rubber blend based on styrene - butadiene (SBR) / natural rubber (NR) with zeolite fillers. The blends with active filler content based on natural zeolites are not implemented in the current practice of tyre production. Procedure of the measurement electrical properties was applied at the temperatures from RT to 200 °C with constant heating rate. The determination of electrical properties by means of the measurements of temperature dependencies of direct current electrical conductivity (σDC=f(T)), were performed using Novocontrol Concept 90. The increase of the values of the electrical conductivity during vulcanization is connected with the increasing of rate of the cross-linking reactions. The rate of reaction is affected by concentration and type of zeolite filler. It is possible to determine significant parameters of cross-linking reactions during vulcanization and also influence of concentration and type of zeolite filler.
Research Interests:
Research Interests:
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... more
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 Co76Si11B13 metallic core and an electroplated Co90Ni10 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.
Research Interests:
There were measured temperature dependencies of the direct electrical conductivity as well as temperature and frequency dependencies of the complex electrical modulus for the pure As - Se - Te glasses and those doped by the rare earth (RE... more
There were measured temperature dependencies of the direct electrical conductivity as well as temperature and frequency dependencies of the complex electrical modulus for the pure As - Se - Te glasses and those doped by the rare earth (RE 3+ ), too. It is clear analyzing the measured dependencies that the mentioned glasses own only one mechanism of the electrical conductivity (type P), with the activation energy U = (0.80 ± 0.05) eV. The gained results of the complex modulus and its compounds make possible to state that the searched glasses are mono-phase but they contain the certain amount of the physical defects. The glasses are the temperature stable up to 160 °C.
Research Interests:
The physical mechanism of photoluminescence spectrum formation of chalcogenide glasses (CHG) belongs to the important unsolved problems in physics of non-crystalline materials. Photoluminescence is an important means of the electron... more
The physical mechanism of photoluminescence spectrum formation of chalcogenide glasses (CHG) belongs to the important unsolved problems in physics of non-crystalline materials. Photoluminescence is an important means of the electron spectrum investigation. PL spectrum in CHG is produced mostly in the middle of the band gap, and its profile is normal - Gaussian. Several features of PL spectra in CHG is still a great mystery. The aim of the paper is to make reader acquainted with the new insight into the problem. In this article we also deal with the issue of clarifying the nature of mid-gap absorption. From the experiments it is known that after excitation of the glass As2S3 (or As2Se3) with primary radiation from Urbach-tail region the glass will be able to absorb the photons of low energy (IR) radiation from mid-gap region of spectra. This low photon absorption without action of the primary excitation radiation of the higher photon energy is impossible. Mid-gap absorption yields boost in the photolumines...
Research Interests:
Oxide and oxyhalide glasses based on antimony oxide, lead halides and alkali oxides have been synthesised and characterised. The direct electrical conductivity and complex electrical modulus have been measured as a function of temperature... more
Oxide and oxyhalide glasses based on antimony oxide, lead halides and alkali oxides have been synthesised and characterised. The direct electrical conductivity and complex electrical modulus have been measured as a function of temperature and chemical composition. The observed differences between samples from the same chemical systems seem correlated to the physical defects which otherwise induce light scattering and decrease in optical transmittance. The accurate observation of the curves expressing the evolution of complex modulus vs. frequency, and real part vs. imaginary part provides information about defects in real samples. This approach may be a useful tool for further glass optimisation.
Research Interests:
Research Interests:
The temperature dependencies of direct electrical conductivity and temperature and frequency dependencies of permittivity of prepared sulphide glasses doped by praseodymium ions (Ge25Ga(10-z)Pr(z)S65 z = 1000 wt. ppm) were measured. The... more
The temperature dependencies of direct electrical conductivity and temperature and frequency dependencies of permittivity of prepared sulphide glasses doped by praseodymium ions (Ge25Ga(10-z)Pr(z)S65 z = 1000 wt. ppm) were measured. The results indicate the existence of one conductivity mechanism with activation energy 0.91 eV up to the temperature 360 °C. The dependencies of electrical modulus M'' versus M' as well as the frequency dependencies M'' versus f show that the glass has monophase structure and. is very homogeneous with the presence of only one relax time. The glass exhibits new relax time distribution iridicating the formation of new structure when it was tempe red up to 380 °C, that means just below Tg = 400 °C.
Research Interests:
The classical model of electrical conduction was used for simulation of alternate conductivity frequency dependence σ(ω) of polymeric material at low frequency range. We assumed that the simple classical kinetic theory is applicable for... more
The classical model of electrical conduction was used for simulation of alternate conductivity frequency dependence σ(ω) of polymeric material at low frequency range. We assumed that the simple classical kinetic theory is applicable for description of drif mobility of the charge carriers bounded in the polymer material structure. Harmonic forced oscillators approximation was used for the simulation of the polymer
Research Interests:
ABSTRACT Sulphide glasses Ge25Ga10S65 doped by ions of rare earths (Pr3+) are suitable for preparing of active optical fibres because they own low phonon energy needed for activation and rather both high value of refractive index and... more
ABSTRACT Sulphide glasses Ge25Ga10S65 doped by ions of rare earths (Pr3+) are suitable for preparing of active optical fibres because they own low phonon energy needed for activation and rather both high value of refractive index and transparency in IR of spectrum. Suitable electrical and dielectric parameters reflect structural changes in tested glasses and aid to determine the influence of various technological parameters and admixtures. The complex electrical modulus can be used for the investigation of the structural changes of Ge25Ga10S65 glasses due to adding of Pr3+ ions. By this method the rise of clusters into glasses can be detected. The admixture begins to segregate to cluster at higher concentration (≥ 3000 wt. ppm). Obtained results of the rise of the clusters agree with the observation by means of electron microscopy. The results of electrical measurements of various samples with low and higher Pr3+ concentration correspond with results obtained by luminescence (influence of rare earth segregation). The measured results unambiguous confirmed that the prepared sulphide glasses are very homogeneous, mono-phase, long-term stable to the high temperature, up to 300 °C at least. The temperature stability at ≤ 1000 wt. ppm Pr3+ up to high temperature remained non-changed. It changed only in the case of the sulphide form of the added admixture ≥ 3000 wt. ppm, when the segregation begun already at temperature of 350 °C.
Research Interests:
Modelling of temperature dependences of direct electrical conductivity of styren-butadien rubber blends from time dependences of torque values during vulcanisation. Repozitář DSpace/Manakin. ...