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[IEEE 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Budapest (2018.7.1-2018.7.5)] 2018 IEEE 2nd International Conference on Dielectrics (ICD) - Influence of Polyhedral Oligomeric Silsesquioxane (POSS) on Space Charge Behavior and Trap Levels of XLPE/POSS nanocomposite
摘要： Polyhedral Oligomeric Silsesquioxane (POSS), a nanometric hybrid molecule, is being paid great attention in the field of polymeric micro and nanodielectrics. In this work, study of spacecharge behavior and trap levels of virgin XLPE and XLPE/OibPOSS (OctalsoButyl Polyhedral Oligomeric SilSesquioxanes) nanocomposites is presented. Two techniques namely Pulse Electro Acoustic (PEA) and Thermal Stimulated Current (TSC) are adopted to illustrate the behavior of space charge and trap levels. Melt blending technique using twin-screw extruder is chosen to make XLPE/POSS nanocomposites in 1wt% and 3wt% concentration of Octaisobutyl POSS(OibPOSS). A low temperature extrusion profile with temperatures (120?-180?) and rotation speed of 100 rpm was maintained in order to achieve XLPE/OibPOSS nanocomposites. TSC data along with the total charge decay data is used to calculate the trap levels inside the composite samples. The results showed similar trap values calculated from both the techniques. It is observed that the POSS has changed the XLPE chain mobility and depth of the charge trapping sites. Mostly, shallow traps are observed in 1wt% and 3wt% samples with charges having a high recombination rate. The charge decay rate is faster in 1wt% and 3wt% samples as compared with virgin XLPE. It is concluded that the interfacial contact formed between different concentrations of POSS and XLPE, and also polymer structure, both are important parameters for industry to consider during manufacturing in order to mitigate the accumulation of traps and spacecharges.
关键词： Polyhedral oligomeric silsesquioxane,cross linked polyethylene,spacecharge,melt blending,thermally stimulated current
更新于2025-09-09 09:28:46
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Optical characterisation of amorphous Se–Te–Sn thin films
摘要： Optical characterization of Sn doped Se–Te thin films has been carried out. The characterization has been carried out using transmission spectra in range 500–2500 nm. Bulk samples were prepared using melt quenching technique and thin films were deposited using thermal evaporation. XRD analysis was used to confirm the amorphous nature of prepared samples. Optical constants such as refractive index and extinction coefficient have been determined using Swanepoel’s method. Variation of refractive index with wavelength has been analysed using single effective oscillator model. Optical band gap of the deposited films was calculated using Tauc plots. The observed properties have been explained using the chemical bond approach.
关键词： Tauc plots,Swanepoel’s method,melt quenching technique,thermal evaporation,Se–Te–Sn thin films,Optical characterization
更新于2025-09-09 09:28:46
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Ultra-wide bandgap, conductive, high mobility, and high quality melt-grown bulk ZnGa <sub/>2</sub> O <sub/>4</sub> single crystals
摘要： Truly bulk ZnGa2O4 single crystals were obtained directly from the melt. High melting point of 1900 ± 20 ?C and highly incongruent evaporation of the Zn- and Ga-containing species impose restrictions on growth conditions. The obtained crystals are characterized by a stoichiometric or near-stoichiometric composition with a normal spinel structure at room temperature and by a narrow full width at half maximum of the rocking curve of the 400 peak of (100)-oriented samples of 23 arcsec. ZnGa2O4 is a single crystalline spinel phase with the Ga/Zn atomic ratio up to about 2.17. Melt-grown ZnGa2O4 single crystals are thermally stable up to 1100 and 700 ?C when subjected to annealing for 10 h in oxidizing and reducing atmospheres, respectively. The obtained ZnGa2O4 single crystals were either electrical insulators or n-type semiconductors/degenerate semiconductors depending on growth conditions and starting material composition. The as-grown semiconducting crystals had the resistivity, free electron concentration, and maximum Hall mobility of 0.002–0.1 ?cm, 3 × 1018–9 × 1019 cm?3, and 107 cm2 V?1 s?1, respectively. The semiconducting crystals could be switched into the electrically insulating state by annealing in the presence of oxygen at temperatures ≥700 ?C for at least several hours. The optical absorption edge is steep and originates at 275 nm, followed by full transparency in the visible and near infrared spectral regions. The optical bandgap gathered from the absorption coef?cient is direct with a value of about 4.6 eV, close to that of β-Ga2O3. Additionally, with a lattice constant of a = 8.3336 ?, ZnGa2O4 may serve as a good lattice-matched substrate for magnetic Fe-based spinel ?lms.
关键词： high mobility,melt growth,high quality,ultra-wide bandgap,conductive,single crystals,ZnGa2O4
更新于2025-09-04 15:30:14