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Abdelaziz Salhi,Salaheddine Sayouri,Lahoucine Hajji,TajEddine Lamcharfi 한양대학교 세라믹연구소 2016 Journal of Ceramic Processing Research Vol.17 No.12
Nanocrystalline barium titanate (BT) was synthesized by the sol gel method. The dry gel obtained was first treated in themicrowave (MW) and then calcined at different temperatures. A pure tetragonal phase was obtained under heat treatmentat 750 oC which is a relatively low temperature. SEM image reveals a fairly dense and uniform microstructure. Dielectricmeasurements performed on the sintered BaTiO3 sample at 1200 oC revealed the presence of the resonance phenomenon atfrequencies lower than 2 MHz and the existence of a weak positive temperature coefficient of resistivity (PTCR) just abovethe Curie temperature. Electric impedance analysis shows the predominance of the grain boundary (gb) contribution andenables determination of activation energies of the gb and the bulk effect and their relative capacitance and resistanceelements.
Abdelhak El Ghandouri,Salaheddine Sayouri,TajEddine Lamcharfi,Lahoucine Hajji 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.2
Structural, dielectric and piezoelectric properties of nanopowders of pure and strontium-doped BaTiO3 (Ba1-xSrx)TiO3 (x =0.00; 0.10; 0.20; 0.30 and 0.40), synthesized by the sol gel process, have been investigated. The samples crystallize in the pureperovskite structure and transform from tetragonal to pseudocubic under doping with Sr. The calculated average crystallitesize was about 30 nm. Dielectric parameters (dielectric permittivity and losses) were determined. Sr doping gives rise to adecrease of the ferro-to-paraelctric transition temperature and to an enhancement of the Positive Temperature Coefficient ofResistivity (PTCR). Piezoelectric parameters were also determined and their thermal behavior investigated.
Fouzia Saadaoui,Salaheddine Sayouri,Abdelilah Rjeb,Badr Akharkhach,Aziz Nfissi 한양대학교 세라믹연구소 2019 Journal of Ceramic Processing Research Vol.20 No.2
In this work, CuO thin films were deposited by sol gel spin-coating technique on microscope glass substrates. Copper acetatewas used as the starting salt material source, ethanol as solvent and monoethanolamine as stabiliser. The as-coated films werepreheated at 300 oC for 10 min and then annealed using two different temperatures. As the annealing temperature wasincreased from 500 oC to 600 oC, along with thickness, an improvement of the structural properties was concluded from XRDand SEM analyses. I-V characteristics of the films corroborated this result and showed existence of a normal Ohmic behaviourof these films. The average crystallite size estimated from XRD analysis was found to increase from 28.06 to 37.68 nm withthe increase of both thickness and annealing temperature. On the other hand, the two parameters dislocation density andstrain followed an opposite trend and decreased from 1.27 to 0.704 (1015 lines /m2) and from 1.29 × 10−3 to 0.961 × 10−3,respectively
Aziz Nfissi,Yahya Ababou,Salaheddine Sayouri,Lamiae Mrharrab,Fouzia Saadaoui,Elmaati Ech-chamikh,Taj-dine Lamcharfi 한양대학교 세라믹연구소 2020 Journal of Ceramic Processing Research Vol.21 No.2
A series of Ce-doped BaTi0.97Y0.03O3 powder samples with the composition (Ba1-xCex)(Ti(0.97-x/4)Y0.03)O3 (x = 0.00, 0.01, 0.03, 0.05,0.07 and 0.09) were prepared using the sol gel process and calcined at a relatively low temperature (950°C/4h) and theirstructural and piezoelectric properties investigated. From structural investigations, it was observed that the samples crystallizein the pseudo cubic phase with the presence of secondary phases for concentrations such as x > 0.03. Piezoelectric parameterswere determined and their thermal behavior investigated. The impedance study indicated the dominance of the resistance ofthe grain boundaries compared to that of grains in BaTi0.97Y0.03O3 sample.
Investigation of the structural and optical properties of sol gel processed Ho-doped BaTiO3 ceramics
Adil Moutaouaffiq,Ali Didi Seddik,Abdelilah Rjeb,Mohammed Naciri Bennani,Mohamed Naji,Salaheddine Sayouri 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.6
The pure BaTiO3 and Ho doped BaTiO3 (Ba1-xHoxTiO3 with x = 0, 0.25, 0.50, 0.75, 1, 1.5 and 2%), powders were preparedthrough the sol-gel process and structurally characterized by Thermogravimetric analysis (TGA), Differential thermal analysis(DTA), X-Ray diffraction (XRD), Fourier Transform Infrared (FT-IR) and Raman spectroscopy. The optical propertieshave been investigated using Ultraviolet-Visible (UV-Vis) transmittance-reflectance spectroscopy. X-ray diffraction (XRD). The results revealed that the prepared powders, calcined at 1000 °C for 4 hours, crystallized in the pure perovskite structurewithout the presence of secondary phases and showed a slight transition from the quadratic phase (pure BT) to the pseudo-cubic phase for the doped samples. From these results, we can also notice that Ho may occupy both Ba and Ti crystallographicsites. Raman and Fourier Transform Infrared (FT-IR) results are in accordance with those obtained from XRDcharacterizations. The values of the bandgap energies for the doped samples are lower than that of the pure BaTiO3 (3.26eV), thus confirming energy softening effect of Ho.