Publications Internationales
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Item Impedance spectroscopy studies on steatite with B 2 O ceramics materials from Algerian palygorskite(International Institute for the Science of Sintering (IISS), 2021) Khalfaoui, K.; Boumchedda, K.; Chaouchi, A.; Saidi, M.; Lamrani, N.B2O3 was used to reduce the sintering temperature of steatite (named MSB) dielectric ceramics. Electrical properties of this composition have been studied using impedance spectroscopic method to get better understanding of the electrical conduction, dielectric relaxation mechanism, and microstructure –electrical properties relationship of the materials as a function of temperature and frequency. These samples were prepared by a solid-state reaction technique and their single phase formation was confirmed by the X-ray diffraction technique. Dielectric and complex impedance spectroscopic studies were carried out in a wide frequency (102-106 Hz) and temperature (30-500oC) range. The dielectric constants decrease with increasing frequency for each sample, and then stabilize at frequencies lower than 100 kHz. The dielectric constant increases with the addition of B2O3. The nature of frequency dependence of ac conductivity of MSB follows the Jonscher power law and calculated DC conductivity follows Arrhinius behavior. The Nyquist plot (Z″ vs Zʹ) revealed the presence only of the grain boundary effect from 350oC onwards. The occurrence of single arc in the complex modulus spectrum of MSB compositions confirms the single-phase characteristics, and also confirms the presence of non-Debye type of multiple relaxations in the materialItem Cu2O addition and sintering temperature dependence of structural, microstructural and dielectric properties of CaCu3Ti4O12 ceramics(Elsevier, 2020) Djafar, Rabah; Boumchedda, K.; Chaouchi, A.; Fasquelle, D.; Sedda, K.; Brahimi, S.; Khalfaoui, K.; Bououdina, M.This study is aimed in the replacement of commonly used (CuO) by Cu2O in the synthesis of perovskite CaCu3Ti4O12 (CCTO) phase by the solid-state reaction method. The XRD analysis of powder calcined at 1100 °C and ceramics sintered at different temperatures show that the CCTO phase was well crystallized with the presence of small quantities of additional phases. The SEM/EDS analysis of prepared pellets show that the formation of Cu2O/CuO phase occurs above 950 °C, resulting in enhanced densification at 1050 °C (>96%). However, it is found that the Cu2O-based CCTO begins to degrade around 1090 °C. The densification after sintering at 1050 °C reaches 96%, meanwhile dielectric constant and loss tangent values are optimum in the low frequency range (<103 Hz); i.e. 13378 and 0.177, respectively. This favors the use of Cu2O instead of CuO in CCTO ceramics for applications at low frequenciesItem Dielectric behavior study of thermosetting matrices loaded(2012) Irekti, Amar; Hami, B.; Aribi, Chouaib; Bezzazi, B.The present study was prospective in nature and its purpose is twofold. It consists, on the one hand, to identify and characterize mineral fillers, secondly, to determine the dielectric properties of materials prepared using the epoxy resin mixed with local inorg anic fillers , very rich in silica such that: sandy, pozzolan, cullet and a small calcium carbonate amount. This application allows us to use the matrix developed as an electrical insulator. The results of our study show that the use of fillers further im proves the dielectric properties of these matrices. After 32 days of conditioning, the values of capacitance and resistance obtained are very remarkable. Comparing our results with previous work with the addition of pure silica, we note that our composites have better properties at a low cost. The hygro - thermal influence is much less important fo r the loaded resin. Our composites may be subject to external environmental influences and they have a range of wide usage in dielectric materials