In this paper we have used the hydrothermal process to synthesize Pb(Fe1/2Nb1/2)O3 ceramics at relatively low temperature. KOH alkaline solution favors the solubility of the precursors in their solid form. The obtained product was put... more
In this paper we have used the hydrothermal process to synthesize Pb(Fe1/2Nb1/2)O3 ceramics at relatively low temperature. KOH alkaline solution favors the solubility of the precursors in their solid form. The obtained product was put into an autoclave and heat treated at 180°C for 24H. The recovered powder was then heat treated at different temperatures to obtain the pure perovskite phase. Reproducibility of the experiment was successfully checked. Microstructure of the samples was analysed with a scanning electron microscope (SEM), and dielectric measurements were performed using an impedance analyser (LCR, HP 4284 A) in the frequency range from 20 Hz to 1MHz.
Research Interests:
In this work, the Pb (Zr 0.52Ti 0.48)1-3x/4Fe x O3 (x=0.0; 0.025; 0.05; 0.075; 0.10; 0.15; 0.20) ceramics were synthesized by using the sol-gel method. X-ray diffraction (XRD), Raman spectra, was used to reach the structural properties of... more
In this work, the Pb (Zr 0.52Ti 0.48)1-3x/4Fe x O3 (x=0.0; 0.025; 0.05; 0.075; 0.10; 0.15; 0.20) ceramics were synthesized by using the sol-gel method. X-ray diffraction (XRD), Raman spectra, was used to reach the structural properties of the studied compounds. The XRD patterns registered at room temperature revealed the phase formation of the samples which was confirmed by the Rietveld refinement method which suggests the formation of mixed tetragonal and rhombohedral phases. Raman spectra show that when iron content increases, the intensity of Raman peaks of pure PZT increases. The dielectric properties of Pb (Zr 0.52Ti 0.48)1-3x/4Fe x (PZTFx) materials as a function of temperature are studied and displayed a resonance phenomenon for all samples which is moved to the higher frequencies combined with a decrease in dielectric constant when Fe concentration increase. The variation of the dielectric constant as a function of temperature at low frequencies reveals a shifting of the tra...
Research Interests:
Research Interests:
Research Interests:
The organic–inorganic hybrid perovskite-like [C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>]<sub>2</sub>ZnCl<sub>4</sub>... more
The organic–inorganic hybrid perovskite-like [C<sub>6</sub>H<sub>5</sub>C<sub>2</sub>H<sub>4</sub>NH<sub>3</sub>]<sub>2</sub>ZnCl<sub>4</sub> (PEA-ZnCl<sub>4</sub>) was synthesized by saturated solutions method. X-ray powder diffraction, Raman spectroscopy, UV-visible transmittance, and capacitance meter measurements have been used to characterize the structure, the functional groups, the optical parameters, and the dielectric constants of the material. The material has a layered structure. The optical transmittance (T %) was recorded and applied to deduce the absorption coefficient (α) and optical band gap (Eg). The hybrid shows an insulator character with a direct band gap about 4.46 eV, and presents high dielectric constants up to a frequency of about 10<sup>5</sup> Hz, which suggests a ferroelectric behavior. The reported optical and dielectric properties can help to under...
Research Interests:
Research Interests:
In this work, the influence of zinc doping on structural and dielectric properties of CaCu(3-x)ZnxTi4O12 (CCZxTO with x = 0, 2.5, 5, 7.5, 10, 12.5 and 15%) ceramics sintered at 1000 ºC for 8 h was studied. The ceramic samples were... more
In this work, the influence of zinc doping on structural and dielectric properties of CaCu(3-x)ZnxTi4O12 (CCZxTO with x = 0, 2.5, 5, 7.5, 10, 12.5 and 15%) ceramics sintered at 1000 ºC for 8 h was studied. The ceramic samples were prepared by the conventional solid-state and calcined at 1050 ºC for 4 h. The X-ray diffraction (XRD) analysis of pure and Zn-doped CCTO were analyzed by using Rietveld refinement with cubic CCTO phase with no trace impurity phase. The scanning electron microscopy (SEM) investigation showed that for Zn-doped CCTO, the grains distributions were homogenous with average sizes which decreased with increasing of Zn concentration. The dielectric permittivity as function of temperature showed two dielectric anomalies (weakly and strong) and the dielectric constant value largely decreased for x = 2.5%, which is about tree magnitude smaller than the pure ceramic. Then it increased and reached a maximum at x = 10%, which is larger than the value of pure ceramic. And...
Research Interests:
The effect of doping sol gel processed (Ba 1-x Sr x )TiO 3 (BST) samples with Cerium (Ce), on both structural and dielectric properties, is investigated. XRD measurements show that the samples crystallize in a pseudo cubic phase with the... more
The effect of doping sol gel processed (Ba 1-x Sr x )TiO 3 (BST) samples with Cerium (Ce), on both structural and dielectric properties, is investigated. XRD measurements show that the samples crystallize in a pseudo cubic phase with the presence of secondary phases. SEM Micrographs revealed that introduction of Ce decreases the grain size; the latter is quite uniform. Moreover, Ce reduces the permittivity of the samples, and an anomaly is observed above 300°C.
Research Interests:
Compositions of La-modified lead zirconate titanate ceramics (PLZT, % La: 0, 0.03, 0.12, 0.20) near the morphotropic boundary phase (MPB) have been prepared using the hydrothermal process. Characterizations using x-ray diffraction (XRD)... more
Compositions of La-modified lead zirconate titanate ceramics (PLZT, % La: 0, 0.03, 0.12, 0.20) near the morphotropic boundary phase (MPB) have been prepared using the hydrothermal process. Characterizations using x-ray diffraction (XRD) and scanning electron microscopy (SEM) have shown that the raw powders present a crystalline structure and exhibit a mixed phase - tetragonal and rhombohedral phases - under heating, and that these powders consist in small particles. Besides, Ladoping have led to a lowering of the temperature of the maximum of the dielectric constant and to an increase of this maximum.
Research Interests:
International audienc
Research Interests:
International audienc
National audienc
Research Interests:
Les poudres ceramiques de titanate de plomb, dopees au lanthane La (PLT), et / ou au fer Fe (PFxT ou PLyFxT), de structure perovskite, ont ete preparees par voie sol-gel en adoptant le mode de la destabilisation de solution colloidale... more
Les poudres ceramiques de titanate de plomb, dopees au lanthane La (PLT), et / ou au fer Fe (PFxT ou PLyFxT), de structure perovskite, ont ete preparees par voie sol-gel en adoptant le mode de la destabilisation de solution colloidale (DSC). L'effet de la temperature sur les echantillons a ete etudie par spectroscopie infrarouge a transformee de Fourier (IRTF). L'effet du dopage en La ou Fe sur la structure cristalline a ete examine par diffraction des rayons X (DRX) et par spectroscopie Raman. Nous avons choisi d'effectuer les mesures dielectriques sur trois echantillons pour voir l'effet d'un faible dopage en fer et d'un fort dopage en lanthane sur les proprietes dielectriques des materiaux PbTiO 3 .
Research Interests:
La-modified lead zirconate titanate ( PZT) ceramics have been prepared using the hydrothermal process. Temperature effect on PLZT powders has been studied using TGA-TDA technics, Fourier Transform Infrared (FTIR) spectroscopy, and X-Ray... more
La-modified lead zirconate titanate ( PZT) ceramics have been prepared using the hydrothermal process. Temperature effect on PLZT powders has been studied using TGA-TDA technics, Fourier Transform Infrared (FTIR) spectroscopy, and X-Ray Diffraction (XRD).Dielectric measurements have also been performed. Crystallization temperature has been found to be inferior to that reported in the literature, relative to analogous compounds prepared using other methods. All the obtained results have been discussed and compared to those reported in the literature.
Research Interests:
As a lead-free ceramic, lanthanum-modified barium titanate (BLT) has attracted significant attention among researchers in recent years due to its interesting ferroelectric and piezoelectric properties and insulating behavior, which can be... more
As a lead-free ceramic, lanthanum-modified barium titanate (BLT) has attracted significant attention among researchers in recent years due to its interesting ferroelectric and piezoelectric properties and insulating behavior, which can be improved by the doping effect. For that, (Ba0.7La0.3) (Ti1−xNix)O3 (where x = 0%, 1%, 3%, 5%, 7% or 10%), denoted as BLTNx, were synthesized via the sol-gel process. The effect of the divalent ion Ni2+ on the structural, microstructural and dielectric properties was investigated by x-ray diffraction (XRD) and Fourier transform infrared (FTIR), Raman, and impedance spectroscopy (IS). Surface morphology analysis is done by scanning electronic microscopy (SEM). Dielectric properties were determined in the ranges 28°C to 400°C and 1 kHz to 2 MHz. The results showed that a low doping amount of Ni (x < 5%) increases the dielectric constant. The sample with x = 5% exhibited, at 400°C, a relatively high dielectric constant (ɛ′ = 2202), the sample with x = 3% exhibited, at 100°C, low dielectric loss (tan(δ) = 0.009), and high insulating character, indicating a suitable material for multilayer ceramic capacitors (MLCCs) and energy storage.
Research Interests:
In this paper, composite ceramics (1-x)CaCu3Ti4O12–(x)PbZr0.48Ti0.52O3 (with x =0.00, 0.50 and 1.00), denoted CCTO-PZT, were prepared by a three-stages modified method, in order to achieve high dielectric constant and low loss.... more
In this paper, composite ceramics (1-x)CaCu3Ti4O12–(x)PbZr0.48Ti0.52O3 (with x =0.00, 0.50 and 1.00), denoted CCTO-PZT, were prepared by a three-stages modified method, in order to achieve high dielectric constant and low loss. Structural investigations carried out by X-ray diffraction (XRD), and FT-IR spectroscopy showed the formation of pure cubic and tetragonal phases for x = 0.00 and x=1.00 compositions, respectively. XRD showed the coexistence of both phases in the CCTO-PZT composite. The morphology of the ceramics was examined by scanning electron micrograph (SEM), results reveal a homogeneous microstructure with two types of grains corresponding to PZT (smaller grains) and CCTO (large grains). Dielectric measurements carried out by an impedance analyzer; show that the dielectric constant of the CCTO-PZT composite is higher than the pure samples (CCTO and PZT) one. The temperature dependence of the ac conductivity indicated that the conduction follows the Arrhenius law and t...
Research Interests:
Research Interests:
Research Interests:
Structural and microstructural properties of sol gel processed BS x T (x = 0.0, 0.05) ceramics have been investigated. Dielectric properties of these ceramics have also been studied as functions of frequency [1kHz-2MHz] at different... more
Structural and microstructural properties of sol gel processed BS x T (x = 0.0, 0.05) ceramics have been investigated. Dielectric properties of these ceramics have also been studied as functions of frequency [1kHz-2MHz] at different measurement temperatures (30-200° C). Heat treatment duration effect on dielectric properties and structural ones has been investigated. The results show that heat treatment and its duration has significant effects on structural, dielectric properties and the average grain size of the samples. Scanning electron microscopy (SEM) analysis show quite regular morphology of the grains and an average grain size which decreases with introduction of Sr, in agreement with structural characterization. Raman analysis has given results which are in accordance of XRD and SEM characterizations. Moreover, the permittivity variations as functions of the frequency, show a decrease in the interval [1kHz-100kHz], followed by an anormal increase in the interval [100kHz-1MHz].
Research Interests:
Research Interests:
Research Interests:
In present work, the structural and dielectric properties of Pb1-xCuxZr0.52Ti0.48O3 (PCxZT) ceramics where x = 0. 0.025, 0.05, 0.075, 0.10, 0.15 and 0.20 were studied. Powder of the compositions (PCxZT) was obtained by sol-gel route, the... more
In present work, the structural and dielectric properties of Pb1-xCuxZr0.52Ti0.48O3 (PCxZT) ceramics where x = 0. 0.025, 0.05, 0.075, 0.10, 0.15 and 0.20 were studied. Powder of the compositions (PCxZT) was obtained by sol-gel route, the powders were calcined at 700 ºC for 4 h and sintered at 1100 ºC for 4 h. X-ray diffraction analysis and Raman spectroscopy suggest the formation of mixed-phase of tetragonal and rhombohedral structure which was confirmed by Rietveld refinement. Dielectric measurements of the compounds were studied as a function of temperature (from room temperature to 420 ºC at different frequencies) and as a function of frequency (from 100 Hz to 2 MHz at different temperatures). The temperature variation of the real permittivity gives evidence of the ferroelectric phase transition as well as of the resonance behaviour also observed in the dielectric permittivity frequency-dependent variation.
Research Interests:
Nano-ceramic Pb0.96La0.04Fe0.03Ti0.97O3 (PL4F3T) was prepared by Sol-Gel reaction method. Raman and XRD patterns of PL4F3T ceramic showed that a single-phase was formed exhibiting a pseudo-cubic crystal structure. With SEM, we examined... more
Nano-ceramic Pb0.96La0.04Fe0.03Ti0.97O3 (PL4F3T) was prepared by Sol-Gel reaction method. Raman and XRD patterns of PL4F3T ceramic showed that a single-phase was formed exhibiting a pseudo-cubic crystal structure. With SEM, we examined the micro-structural properties. The electrical behavior was investigated by the impedance spectroscopy in the range of 50°C 600°C. This study was carried out by analysis of the complex impedance (Z*) from the measurement range of 1 kHz to 1 MHz. Complex analysis provides wider information related to charge transport processes.
The effect of Barium doping is studied on ferroelectric properties of (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 with( x = 0.00; 0.0 3; 0.05; 0.06; 0.07; 0.08 and 0.10) prepared through solid state sintering route. X-ray diffraction along with... more
The effect of Barium doping is studied on ferroelectric properties of (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 with( x = 0.00; 0.0 3; 0.05; 0.06; 0.07; 0.08 and 0.10) prepared through solid state sintering route. X-ray diffraction along with Rietveld refinement revealed a gradual change in crystal structure from rhombohedral to tetragonal with increasing BaTiO3 doping in the compound. SEM images have shown a uniform distribution of grains and change in grain size with BaTiO3 concentration. Dielectric and dispersive studies have been carried out. The rhombohedral distortion of the unit cell slightly increased and ferroelectric transition temperature, Tm decreased with the increase of Barium content and all compositions of (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3ceramic materials reveal diffuse phase transition that is marked by a strong frequency dispersion of the permittivity which would be related with the cation disorder in the A site of the unit cell. Combined impedance and electrical propriety were ...
Perovskite ceramic materials of the composition Pb1-xSrxTiO3 (PSxT) were prepared by hydrothermal process at a relatively low temperature. The solution of KOH favours the solubility of the precursors in solid state. Pressure and... more
Perovskite ceramic materials of the composition Pb1-xSrxTiO3 (PSxT) were prepared by hydrothermal process at a relatively low temperature. The solution of KOH favours the solubility of the precursors in solid state. Pressure and temperature are critical factors for the formation of pure perovskite PSxT phase. The reaction mixture in stoichiometric amount is put in an autoclave and treated at 180 ºC for 24 h. The powder obtained after grinding is treated at 400 ºC for 4 h. X-ray diffraction shows that the compounds crystallize in a pure phase of perovskite type. SEM morphology indicates a homogeneous microstructure of the grains with the presence of pores. The impedance spectroscopy study in the frequency range (1 KHz − 2 MHz) confirms the insertion of stronium into the lead titanate matrix and highlights the strontium effect on the transition temperature (Tc) and the value of dielectric permittivity (εr).
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
Research Interests:
The Miocene marls or calcareous clay of the southern Rif groove is one of the geological wealth of the two regions of Fez in Morocco. For greater industrial development in Fez regions the present study on calcareous clays was undertaken.... more
The Miocene marls or calcareous clay of the southern Rif groove is one of the geological wealth of the two regions of Fez in Morocco. For greater industrial development in Fez regions the present study on calcareous clays was undertaken. Physical and chemical characterization of this clay was carried out before and after doping with MnO 2 following various analytical techniques such as X-ray diffraction (XRD), scanning (SEM) and transmission electron microscope (TEM). The doping of the clays was done at different percentages (5%, 10% and 15%) of MnO 2. The results of the mineralogical analysis of clays before and after this doping show that the peaks appear for pyrolusite. Further characterization of the nano clays by TEM before and after doping, indicated the different nano organization of these oxides in the clay matrix.
The sintering effect on transition parameters and dielectric characteristics of Ba(Zr 0.05 Ti 0.95)O 3 (BZT-5%) ceramics prepared by the sol-gel reaction technique was studied. With X-ray diffraction we studied the influences of sintering... more
The sintering effect on transition parameters and dielectric characteristics of Ba(Zr 0.05 Ti 0.95)O 3 (BZT-5%) ceramics prepared by the sol-gel reaction technique was studied. With X-ray diffraction we studied the influences of sintering time on grain size and structural parameters. The phase transitions and dielectric properties were investigated by measuring the real part of dielectric constant ε' and the loss factor tanδ as a function of temperature (30-200 °C) at long range of frequency (1kHz-2MHz). Two different conduction mechanisms were obtained by fitting the complex impedance data to Cole-Cole equation. The grain and grain boundary resistivity were found to follow the Arrhenius law associated with activation energies: E a2 below and above T m for the bulk conduction; and E a1 below T m for the grain boundary conduction. Relaxation times extracted using imaginary part of complex dielectric constant ε " (ω) were also found to follow the Arrhenius law and showed an a...
The binding energy of an exciton in a cubic quantum dot has been calculated with and without including the electron (hole)-confined longitudinal optical phonon interactions, using a variational approach and within the effective mass... more
The binding energy of an exciton in a cubic quantum dot has been calculated with and without including the electron (hole)-confined longitudinal optical phonon interactions, using a variational approach and within the effective mass approximation. The quantum confinement effect is described by an infinitely deep well in the envelope-function approximation. The charge carrier phonon coupling is treated within the adiabatic approximation. As the dot size increases, the results show that the contribution of the confined longitudinal optical phonon on the binding energy decreases and the correction to the excitonic state increases.
Research Interests:
(Pb1 − xLax)Ti1 − x/4O3 (PLTx) ceramics of perovskite type were prepared by sol-gel process, and their structural and dielectric properties investigated. Calcinations of the powders were done in the temperature range of 400–700°C. The... more
(Pb1 − xLax)Ti1 − x/4O3 (PLTx) ceramics of perovskite type were prepared by sol-gel process, and their structural and dielectric properties investigated. Calcinations of the powders were done in the temperature range of 400–700°C. The obtained compounds crystallize, under heat treatment, at relatively low temperatures and no secondary phases have been observed on the corresponding XRD spectra. Dielectric measurements revealed
Research Interests:
ABSTRACT Magnesium (Mg) doped lead titanate powders (PT: Mg) ceramics, with various Mg contents (0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, and 30 mole %), are prepared by the sol-gel method and characterized by X-Ray diffraction (XRD),... more
ABSTRACT Magnesium (Mg) doped lead titanate powders (PT: Mg) ceramics, with various Mg contents (0, 2.5, 5, 7.5, 10, 12.5, 15, 17.5, 20, and 30 mole %), are prepared by the sol-gel method and characterized by X-Ray diffraction (XRD), scanning electron microscopy (SEM) and Raman spectroscopy. XRD results show that the magnesium diminishes the lattice tetragonality of PT:Mg. The average particle size and morphology were studied by SEM. The investigations done by Raman spectroscopy allow the analyzis of the substitution mechanism behavior related to the Mg incorporation into PT structure. A concentration threshold appears around 10% of Mg corresponding in a change of the compensation process with Mg2+ ions replacing Pb2+ ions below and both Pb2+ and Ti4+ above. (© 2011 WILEY-VCH Verlag GmbH &amp; Co. KGaA, Weinheim)
Research Interests:
Research Interests:
Research Interests:
The binding energy of an exciton in a cubic quantum dot has been calculated with and without including the electron (hole)-confined longitudinal optical phonon interactions, using a variational approach and within the effective mass... more
The binding energy of an exciton in a cubic quantum dot has been calculated with and without including the electron (hole)-confined longitudinal optical phonon interactions, using a variational approach and within the effective mass approximation. The quantum confinement effect is described by an infinitely deep well in the envelope-function approximation. The charge carrier phonon coupling is treated within the adiabatic approximation. As the dot size increases, the results show that the contribution of the confined longitudinal optical phonon on the binding energy decreases and the correction to the excitonic state increases.
Research Interests:
The Miocene marls or calcareous clay of the southern Rif groove is one of the geological wealth of the two regions of Fez in Morocco. For greater industrial development in Fez regions the present study on calcareous clays was undertaken.... more
The Miocene marls or calcareous clay of the southern Rif groove is one of the geological wealth of the two regions of Fez in Morocco. For greater industrial development in Fez regions the present study on calcareous clays was undertaken. Physical and chemical characterization of this clay was carried out before and after doping with MnO 2 following various analytical techniques such as X-ray diffraction (XRD), scanning (SEM) and transmission electron microscope (TEM). The doping of the clays was done at different percentages (5%, 10% and 15%) of MnO 2. The results of the mineralogical analysis of clays before and after this doping show that the peaks appear for pyrolusite. Further characterization of the nano clays by TEM before and after doping, indicated the different nano organization of these oxides in the clay matrix.
Structural and microstructural properties of sol gel processed BS x T (x = 0.0, 0.05) ceramics have been investigated. Dielectric properties of these ceramics have also been studied as functions of frequency [1kHz-2MHz] at different... more
Structural and microstructural properties of sol gel processed BS x T (x = 0.0, 0.05) ceramics have been investigated. Dielectric properties of these ceramics have also been studied as functions of frequency [1kHz-2MHz] at different measurement temperatures (30-200° C). Heat treatment duration effect on dielectric properties and structural ones has been investigated. The results show that heat treatment and its duration has significant effects on structural, dielectric properties and the average grain size of the samples. Scanning electron microscopy (SEM) analysis show quite regular morphology of the grains and an average grain size which decreases with introduction of Sr, in agreement with structural characterization. Raman analysis has given results which are in accordance of XRD and SEM characterizations. Moreover, the permittivity variations as functions of the frequency, show a decrease in the interval [1kHz-100kHz], followed by an anormal increase in the interval [100kHz-1MHz].