Publications Scientifiques

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    Tuning the dielectric properties of CaCu3Ti4O12 ceramic by Cu2O addition and microstructural modifications
    (Elsevier, 2023) Djafar, Rabah; Boumchedda, K.; Fasquelle, D.; Chaouchi, A.; Sedda, K.; Bououdina, M.; Bellucci, S.
    Cuprous (I) oxide (Cu2O) was used instead of Cupric (II) oxide (CuO) for the synthesis of CCTO ceramic by solid-state reaction. The impact of sintering time on the structure stability, grain size, and dielectric performance of Cu2O-based CCTO ceramics was discussed. XRD analysis indicates that the CaCu3Ti4O12 cubic phase was successfully synthetized. The studied samples manifested high permittivity and quite low dielectric loss values in the frequency range (20–106 Hz); with optimum values of 15,423 and 0.083 respectively achieved after sintering at 1050 °C for 14 h while for longer sintering times of 19 h and 24 h resulted in higher values of permittivity of 19,943 and 21,392 respectively were obtained and associated with an improved loss tangent of ∼0.114 and 0.127, respectively. It was found that a longer sintering time of Cu2O-based CCTO ceramics resulted in an important improvement of the dielectric properties
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    Dielectric properties of nanocrystalline CaCu3Ti4O12 (CCTO) ceramics fabricated from Algerian limestone raw material
    (Elsevier, 2023) Djafar, Rabah; Boumchedda, K.; Fasquelle, D.; Chaouchi, A.; Sedda, K.; Bououdina, M.; Bellucci, S.; Bánhegyi, G.
    Algerian natural limestone was used to fabricate the perovskite CaCu3Ti4O12 phase (CCTO) to replace commercial calcium carbonate (CaCO3) powder by a solid-state method. X-ray diffraction analysis of CCTO ceramics sintered at 1010 °C manifested the formation of well-crystallized pure (CCTO) phase with narrow crystallite size (43–99 nm) without any additional phases after sintering beyond 4 h. Thermal analysis by DSC indicated that CCTO phase is stable up to 1151 °C, afterwards it decomposes into CaTiO3 and TiO2 and accompanied by the segregation of the CuO/Cu2O phase. Scanning electron microscopy observations of the ceramics sintered at 1010 °C showed that most of the grains have an average particle size in the narrow range of 1–2 μm. The sintered pellet at 1010 C° for 14 h showed the optimum density (>94%). This study highlights the importance of using natural calcium carbonates (extracted from Guelma limestone in Algeria) as potential replacement to commercial counterpart for the fabrication of dense well-crystallized perovskite-type ceramics with controlled particle size distribution as promising candidates for electronic applications
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    Synergistic effect of Rutile-Anatase Fe-doped TiO2 as efficient nanocatalyst for the degradation of azucryl red
    (IOP Publishing, 2019) Kerrami, Ahmed; Mahtout, Laila; Bensouici, F.; Bououdina, M.; Rabhi, S.; Sakher, E.; Belkacemi, H.
    The aim of this work is to reduce the impact on the environment of a basic textile dye (azucryl red) using a semiconductor TiO2 and Fe doped TiO2 powders calcined at 600 °C as catalysts. The refinements based on the Rietveld method of x-ray diffraction patterns indicate the formation of Rutile phase for un-doped TiO2, while a phase transformation into Anatase phase occurs upon Fe doping. Scanning electron microscopy analysis reveals the formation of spherical-like particles at the nanoscale that agglomerate into aggregates, meanwhile the chemical composition checked by EDX spectroscopy is close to the stoichiometry. FTIR analysis reveals the presence of OH groups that favor the photocatalytic reaction, while EPR analysis confirms the existence of Fe3+ resulting in the creation of oxygen vacancies. Excellent photocatalytic degradation of azucryl red is obtained by 0.2% Fe doped TiO2, the removal of 100% of dye is achieved within a very short time of 10 min
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    Effect of Er doping on the microstructural, optical, and photocatalytic activity of TiO2 thin films
    (Iop science, 2018) Abdelali, Aouina; Bensouici, F.; Bououdina, M.; Tala-Ighil, Razika
    anostructured Er³⁺ doped TiO2 thin films are deposited onto glass substrate via sol-gel dip-coating followed by calcination at 450 °C for 1 h. X-ray diffraction analysis confirms that the films crystallized within single tetragonal anatase phase. Atomic force microscopy observations reveal that the surface of pure TiO2 is characterized by ninepins then becomes smooth and porous for Er-doped TiO2 thin films, while the roughness decreases drastically from 17.2 to 2.6 nm with increasing Er³⁺ percentage. Wettability tests show a super-hydrophilicity character of 0.2 and 0.3%Er doped TiO2 thin films. UV–vis analysis reveals high transmittance above 85% with the presence of interferences indicating the high quality of films. Meanwhile, the energy band gap decreases slightly from 3.31 eV for un-doped to 3.26 eV for 0.4%Er, with a red-shift in the optical absorption edge. High photocatalytic activity using methylene blue indicator has been achieved for 0.2% Er³⁺–TiO2 thin film, reaching 95% for 3 h.