“…1 . The results demonstrate that there is not any sharp peak of crystalline in the curve, and there is a broad hump between 20 and 40° which confirms the noncrystalline (amorphous) nature of the prepared glasses [ 28 , 29 ]. Fig.…”
“…1 . The results demonstrate that there is not any sharp peak of crystalline in the curve, and there is a broad hump between 20 and 40° which confirms the noncrystalline (amorphous) nature of the prepared glasses [ 28 , 29 ]. Fig.…”
“…Ec is the activation energy for electrical conductivity, expressed in J/mol. Considering the articles of other authors 4 , 10 , 44 – 47 , some vanadate and phosphate-tellurite glasses can exhibit also ionic conductivity in addition to the much more important electronic conductivity. This ionic conductivity is due to the migration of non-bridging oxygen along the network-former chains 45 , 46 or to the ion hopping of oxygen vacancies 47 .…”
Section: Resultsmentioning
confidence: 98%
“…The increase of conductivity with temperature is signaled also by Barde 10 for vanadium-boron-phosphate glasses with 60 % vanadium oxide. The linear variation of the conductivity with temperature can indicate the presence of an ionic charge transfer mechanism, due to the migration of non-bridging oxygen, via an activated hopping mechanism 44 – 47 .…”
Vanadate glasses exhibit semiconducting property at certain temperatures. This work demonstrates the conductivity of the composition 45V2O5–25B2O3–30P2O5, which is a new glass in the vanadium-boron-phosphorus ternary system that expands the glass forming area reported in literature data. The glass was obtained through a classical melt-quenching technique. The structural composition of the obtained glass was revealed with Raman spectroscopy and the amorphous characteristic has been highlighted with X-ray diffraction. The characteristic temperatures and the thermal expansion coefficient were determined by dilatometry. Based on the experimental measurements of electrical resistance, mathematical calculations were performed, resulting in a conductivity of 2.04·10−6 S/cm at 125 °C, and an activation energy of 42.91 kJ/mol for this glass. Impedance spectroscopy in DC and AC at 100 V and 100 Hz to 2 MHz, respectively, showed a lower activation energy of about 0.166 eV and transition temperatures of 24 °C and 11 °C, respectively. These results were compared with those from the literature considering the temperatures at which the reported conductivities were measured. This glass has potential applications in electronic devices and temperature sensors.
“…IOP Publishing doi:10.1088/1757-899X/1300/1/012045 2 Structural and dielectric properties of phospho-tellurite glasses have also been studied. Utilizing the measured dielectric properties, ac conductivity has been estimated and understood [7]. Addition of tellurium into silver-boro-phospho-tellurite glasses in terms of electrical properties has been studied [8,9].…”
The phospho-tellurite glasses, (P2O5)0.25-(TeO2)0.5-x-(CoO)0.1-(ZnO)0.15-(Na2O)x ; x = 0.15, 0.20, 0.25, 0.30 and 0.35 were prepared by melt quenching and their non-crystalline nature confirmed through XRD. Density is found decreased and molar volume increased with increase of Na2O concentration and they behaved opposite to each other. The physical parameters such as transition metal ion density, mean distance between TMIs, small polaron radius, oxygen packing density and field strength were estimated. DC conductivity was measured by following two probe method in the temperature range 303K – 633K. High temperature conductivity is explained by Mott’s small polaron hopping (SPH) model and low temperature conductivity by Mott’s VRH model. Both conductivity and activation energy are found to be increasing with Na2O content. Density of states at Fermi level are found to be of the order of 1021 to 1024 eV−1 cm−3. UV-Vis spectra were recorded for the wavelength range 200-800 nm. Optical band gap (direct and indirect) except for x=0.20 is found increased, urbach energy and refractive indexes are found decreased with Na2O concentration. Various optical parameters such as molar polarizibility, metallization criterion, reflection loss, electronic polarizability, optical transmission coefficient, dielectric constant and optical dielectric constant have been determined.
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