arXiv subjects

D. Mezzane

Publications and source records attributed to D. Mezzane.

At least 19 recordsLinked to original sources

arXiv2025

Enhancement of the energy storage and electrocaloric effect performances in 0.4 BCZT 0.6 BSTSn medium entropy ceramic prepared by sol gel method

Based on the traditional polycrystalline ferroelectric Ba0.85Ca0.15Zr0.10Ti0.90O3, the 0.4 Ba0.85Ca0.15Zr0.10Ti0.90O3 0.6 Ba0.9Sr0.1Ti0.9Sn0.1O3 medium entropy material with good energy storage and electrocaloric effect performances is designed and synthesized by the solgel method. The structural, dielectric, energy storage and electrocaloric effect properties of the prepared sample were studied. The findings demonstrate that the 0.4 Ba0.85Ca0.15Zr0.10Ti0.90O3 0.6 Ba0.9Sr0.1Ti0.9Sn0.1O3 ceramic simultaneously has a significant recoverable energy storage density of 255.4 mJ/cm3, an efficiency of 67.9%, a large ECE temperature change of 1.36 K, and a high ECE responsivity of 0.453 K.mm/kV under a low electric field of 30 kV/cm. Moreover, excellent temperature stability of Wrec (less than 10%) was achieved in the investigated sample 0.4BCZT 0.6BSTSn.

cond-mat.mtrl-sci↗

arXiv2025

Lithium doping's effects on the microstructural,dielectric,energy storage,optical and electrical properties of BaTi0.89Sn0.11O3 ceramics

This research study the sol/gel synthesis of lithium-doped barium stannate titanate BaTi0.89Sn0.11O3 (BTS11) and investigates how varying composition with lithium affect its structural, morphological, ferroelectric, optical, and electrical properties. The phase of the sol/gel prepared samples with different compositions BaLixTi0.89Sn0.11O3 (BLxTS11), where x = 0%, 2%, 4%, 6%, 8, and 10%, was examined using X-ray diffraction (XRD), which showed the development of a pure perovskite structure. Furthermore, structural characterization was performed with Raman spectroscopy to identify changes in structure and chemical environment resulting from Li incorporation. The doping caused changes in the morphology and grain size of BLxTS11 pellets, as examined through SEM micrographs. These micrographs showed clear alterations in grain size that were inversely related to the lattice strain of BLxTS11. The samples were subsequently examined for their ferroelectric properties. All samples exhibited their maximum dielectric constant at approximately 45-50 {\deg}C. Furthermore, relationships between the chemical, structural, and morphological characteristics of the BLxTS11 ceramics and their energy storage capabilities were identified. Based on the P-E hysteresis behavior, the BL6TS11 ceramic (x=6%) ferroelectric exhibited superior energy-storage capabilities, featuring a recoverable energy-storage density of 225 mJ/cm3 and an energy-storage efficiency of 60%. An examination of the material's optical and electrical properties revealed that Li doping led to a reduction in the band gap values and a considerable increase in resistivity.

cond-mat.mtrl-sci↗

arXiv2025

Improved thermal stability of dielectric properties and energy storage properties of lead-free relaxor Ba(1-x)LaxTi0.89Sn0.11O3 ceramics

Lead-free perovskite ceramics Ba(1-x)LaxTi0.89Sn0.11O3 with x= 0, 0.015, 0.025, and 0.035 (BLTSnx) were synthesized by solid-state reaction method. The enhanced energy storage properties were studied across the ferroelectric relaxor conversion. The pure perovskite structure of all prepared samples was confirmed by X-ray diffraction (XRD) analysis and the Raman spectroscopy technique. Scanning electron microscopy micrographs show a drastic decrease in the grain size in La-doped ceramics. Furthermore, the doped samples exhibit smeared phase transition and frequency dispersion in dielectric permittivity, typical for relaxors. The P-E hysteresis loops become thin with the increase of the La-doping, demonstrating the ferroelectric-relaxor phase conversion. The enhanced recovered energy density and the energy storage efficiency of 158.8 mJ/cm3 and 82.73 % were observed in the BLTSn2.5 sample at room temperature, respectively. These properties indicate that environmentally friendly BLTSn2.5 is a viable candidate for energy-storage capacitor applications near room temperature.

cond-mat.mtrl-sci↗

arXiv2024

Dielectric and energy-storage properties of Ba0.85Ca0.15Zr0.10Ti0.90O3 ceramics with BaO-Na2O-Nb2O5-WO3-P2O5 glass addition

Lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) ceramics with different BaO-Na2O-Nb2O5-WO3-P2O5 (BNNWP) glass content, forming (1-x)BCZT-xBNNWP lead-free ceramics (abbreviated as BCZTx; x=0, 2, 4, 6, and 8wt%) were synthesized using the conventional solid-state processing route. The XRD investigation shows the coexistence of tetragonal and orthorhombic phases in BCZT pure. Likewise, only the tetragonal phase was detected in BCZTx (x = 2-8 wt%) ceramics. The SEM findings indicate that the average grain size decreases as the amount of BNNWP glass additives increases. In addition, BCZT ceramics Amodified with glass additions showed narrower hysteresis loops and a large electric field. The BCZT4 showed the highest recovered energy density of 0.52 J/cm3 at 135kV/cm with an energy storage efficiency of 62.4%, which is increased by 6.6 compared to BCZT0 (0.075 J/cm3). The energy density was also calculated using the Landau-Ginzburg-Devonshire (LGD) theory

physics.app-ph↗

arXiv2023

Structural, dielectric, ferroelectric and electrical properties of lead-free Ba0.9Sr0.1Ti0.9Sn0.1O3 ceramic prepared by sol-gel method

Lead-free Ba0.9Sr0.1Ti0.9Sn0.1O3 (BSTSn) ceramic was prepared by the sol gel method. X-ray diffraction measurement at room temperature reveals the single-phase formation with tetragonal structure refined in the P4mm space group. Raman spectroscopy analysis at room temperature was used to confirm the structure of BSTSn ceramic sintered at 1420C during 5h. The dielectric measurements were examined in the temperature range [-90 250 C] and the frequency range of [100Hz 1MHz]. The maximum dielectric constant was found to be 5484 (1kHz) at room temperature. The diffuse phase transition characteristic at 1kHz was ascribed by the modified Curie Weiss law. Macroscopic polarization field (P E) hysteresis loops recorded at room temperature (RT) confirm the ferroelectric nature of BSTSn ceramic. Impedance spectroscopy analysis of BSTSn sample in the temperature range 300 380 C reveals the presence of two relaxation contributions originated from grains and grain boundaries. Activation energies of grain and grain boundaries resistances were deduced in order to determine the conduction mechanism of the studied sample.

cond-mat.mtrl-sci↗

arXiv2023

Improvement of the electrocaloric effect and energy storage performances in Pb-free ferroelectric Ba0.9Sr0.1Ti0.9Sn0.1O3 ceramic near room temperature

Perovskite-type Ba0.9Sr0.1Ti0.9Sn0.1O3(BSTSn) ceramic was synthesized by the sol gel method. The P E hysteresis loops were recorded at different temperatures to investigate the ferroelectric and energy storage properties of BSTSn ceramic. Enhanced recoverable energy density and high energy storage efficiency were found to be 58.08 mJ/cm3 and 84.36 %, respectively at room temperature (RT) under a moderate applied electric field of 20 kV/cm. The electrocaloric effect (ECE) in the BSTSn ceramic was explored using two different approaches based on P E hysteresis loops, and pyroelectric current measurements. The largest electrocaloric (EC) temperature change of 0.63 K was determined using the Maxwell relationship obtained near RT under 20 kV/cm. The corresponding EC responsivity value of 0.31 K.mm/kV is one of the highest reported values in lead-free ferroelectrics near RT. This study demonstrates that the BSTSn ceramic is a promising candidate for solid-state cooling and energy storage applications.

cond-mat.mtrl-sci↗

arXiv2023

Enhanced thermal stability of dielectric and energy storage properties in 0.4BCZT-0.6BTSn lead-free ceramics elaborated by sol-gel method

Polycrystalline lead-free Ba$_{0.85}$Ca$_{0.15}$Zr$_{0.10}$Ti$_{0.90}$O$_3$ (BCZT), BaTi$_{0.89}$Sn$_{0.11}$O$_3$ (BTSn) and 0.4Ba$_{0.85}$Ca$_{0.15}$Zr$_{0.10}$Ti$_{0.90}$O$_3$-0.6BaTi$_{0.89}$Sn$_{0.11}$O$_3$ (0.4BCZT-0.6BTSn) ferroelectric ceramics were prepared via sol gel process and their structural, dielectric and energy storage properties were studied. Pure perovskite structure was confirmed by X ray diffraction analysis. The evolution of energy storage performances with temperature was studied. A Significant recoverable energy storage density of 137.86 mJ/cm$^3$ and high energy-storage efficiency of 86.19% under a moderate electric field of 30 kV/cm were achieved in the composite 0.4BCZT 0.6BTSn ceramic at 353 $^\circ$K. Moreover, excellent temperature stability (70-130 $^\circ$C) of the energy storage efficiency (less than 3%) was achieved.

cond-mat.mtrl-sci↗

arXiv2020

Enhancing the dielectric, electrocaloric and energy storage properties of lead-free Ba0.85Ca0.15Zr0.1Ti0.9O3 ceramics prepared via sol-gel process

The Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) ceramics were successfully prepared by sol-gel process, and sintered at 1420 degree. The effect of sintering times (2, 4 and 6 h) on structural, microstructural, electric properties, energy storage, and electrocaloric effect was systematically examined. X-ray diffraction (XRD) results show that all the samples crystallize in the pure perovskite structure. The morphotropic phase transition from the tetragonal to the orthorhombic phase (T-O) was identified and confirmed by Rietveld refinement. The BCZT ceramic sintered at 1420 degree for 4h possesses a good relative density of 98%, and exhibits optimal properties with a high dielectric permittivity ~16310, a large electrocaloric effect coefficient ~ 0.244Kmm/kV and an energy density storage of ~ 10.61 mJ/cm3.

cond-mat.mtrl-sci↗

arXiv2020

The electrocaloric response in Lanthanum-modified lead zirconate titanate ceramic

Over the past decades, there has been significant interest in new cooling technology based on the electrocaloric effect. The large electrocaloric effect observed in polymeric and inorganic ferroelectric materials made possible development of dielectric cooling devices of a new generation. We report a significant impact of annealing on the electrocaloric effect observed in 12/65/35 PLZT bulk ceramics. The electrocaloric data were obtained by direct measurements. Electrocaloric results confirm the existence of the significant electrocaloric response in this relaxor ferroelectric PLZT composition exceeding previously obtained electrocaloric values in perovskite relaxor ferroelectrics such as PMN-PT and x/65/35 PLZT ceramics.

cond-mat.mtrl-sci↗

arXiv2020

Mean field theory and Monte Carlo simulation of Phase transitions and Magnetic Properties of a tridimensional Fe7S8 Compound

The structural, electronic and magnetic properties of Fe7S8 material have been studied within the framework of the ab-initio calculations, the mean field approximation (MFA) and Monte Carlo simulation (MCS). Our study shows that two forms of the iron atoms, Fe2+ with spin S=2, and Fe3+ with spin σ=5/2 are the most probable configurations. A mixed Ising model with ferromagnetic spin coupling between Fe2+ and Fe3+ ions and between Fe3+ and Fe3+ ions, and with antiferromagnetic spin coupling between Fe2+ ions of adjacent layers has been used to study the magnetic properties of this compound. We demonstrated that the magnetic phase transition can be either of the first or of the second order, depending on the value of the exchange interaction and crystal field. The presence of vacancies in every second iron layer leads to incomplete cancellation of magnetic moments, hence to the emergence of the ferrimagnetism. Anomalies in the magnetization behavior have been found and compared with the experimental results.

cond-mat.mtrl-sci↗

arXiv2020

Structural, dielectric and magnetic studies of (0-3) type multiferroic (1-x) BaTi0.8Sn0.2O3-(x) La0.5Ca0.5MnO3 (0 <x< 1) composite ceramics

Multiferroic composites with the composition (1-x) BaTi0.8Sn0.2O3 - (x) La0.5Ca0.5MnO3 (x =0, 0.3, 0.5, 0.7, 0.9 and 1) were prepared by sol-gel techniques. Rietveld refinements of the composites with 0-3 and 3-0 type connectivities exhibit the formation of pure phases and confirm the fraction of the composite samples. It was found that the composites grain size decreases slightly with increasing the La0.5Ca0.5MnO3 content. Magnetic measurements of the composite ceramics exhibit a gradual increase in saturation and remanent magnetization with increasing La0.5Ca0.5MnO3 content. Dielectric data demonstrate that the composite materials show high values of the dielectric constant in comparison with the parent compound BaTi0.8Sn0.2O3 (BTSO). In addition, an attempt is made to measure the magnetoelectric coupling coefficient and to explain the negative permittivity and losses occurring in these materials at a certain frequency and temperature conditions.

cond-mat.mtrl-sci↗

arXiv2020

Structural, dielectric, ferroelectric and tuning properties of Pb-free ferroelectric Ba0.9Sr0.1Ti1-xSnxO3

A series of Pb-free ferroelectric materials Ba0.9Sr0.1Ti1-xSnxO3 (BSTS-x) with 0 < x < 0.15 was successfully prepared via solid-state reaction method. The effect of Sn substitution on the crystal structure, microstructure, dielectric behavior, ferroelectric and tunable features of BSTS-x ceramics were systematically investigated. Room temperature (RT) x-ray diffraction (XRD) analysis using the Rietveld refinement method reveals that all the synthesized BSTS-x ceramics were well crystallized into single perovskite structure. The results show a tetragonal phase for 0.00 < x < 0.02, which evolves to orthorhombic and tetragonal coexisting phases for 0.05 < x < 0.07. The composition x = 0.10 showed a mixture of tetragonal, orthorhombic and rhombohedral phases at RT, while a single cubic phase is observed for x = 0.15. The crystal phases determined by XRD were confirmed by Raman spectroscopy. Enhanced dielectric permittivity with a maximum value of ε'~ 35000 is observed for x = 0.10 at RT. The ferroelectric behavior of BSTS-x ceramics was investigated through polarization hysteresis loops and tunability measurements. High tunability of 63% at RT and under the low DC-applied electric field of 1.40 kV/cm is achieved for x = 0.10.

cond-mat.mtrl-sci↗

arXiv2020

Electrocaloric response in Lanthanum-modified lead zirconate titanate ceramics

Recent findings of a large electrocaloric (EC) effect in polymeric and inorganic ferroelectric materials open a potential possibility of development of solid-state cooling or heating devices of new generation with better energy efficiency that may be less harmful for the environment. We investigate by using direct measurements, the temperature and electric field dependence of the electrocaloric response in Pb1-xLax(ZryTi1-y)1-x/4O3 bulk ceramics (PLZT) with x=0.06 and 0.12. Here, the properties of the EC response were probed in a part of the PLZT composition phase diagram with low y=0.40 composition, in which the EC effect was not previously studied. Measurement results show the existence of the sizeable EC response in 12/40/60 PLZT sample with the EC temperature change (ΔTEC) of 2.92 K at 430 K and 80 kV/cm. This value exceeds previously obtained ΔTEC values in relaxor ferroelectric x/65/35 PLZT compositions and rivaling the best EC response in lead magnesium niobate-lead titanate ceramics. The electrocaloric responsivity (ΔT/ΔE) value of 0.41x10-6 Km/V determined at a lower electric field of 20 kV/cm and 410 K is comparable to those observed in other perovskite ferroelectrics.

cond-mat.mtrl-sci↗

arXiv2019

Synthesis of La0.5Ca0.5-x xMnO3 nanocrystalline manganites by sucrose assisted auto combustion route and study of their structural, magnetic and magnetocaloric properties

Perovskite manganite La0.5Ca0.5-x xMnO3 (LCMO) nanomaterials were elaborated using the sucrose modified auto combustion method. Rietveld refinements of the X-ray diffraction patterns of the crystalline structure confirm a single-phase orthorhombic state with Pbnm space group (No. 62). The Ca-vacancies were voluntarily created in the LCMO structure in order to study their influence on the magnetic behaviour in the system. The magnetic susceptibility was found to be highly enhanced in the sample with Ca-vacancies. Paramagnetic-to-ferromagnetic phase transition was evidenced in both samples around 254 K. This transition is, characterized by a drastic jump of the susceptibility in the sample with Ca-vacancies. The maximum of entropy change, observed for both compounds at magnetic field of 6T was 2.30 J kg-1K-1 and 2.70 J kg-1K-1 for the parent compound and the lacunar one respectively. The magnetocaloric adiabatic temperature change value calculated by indirect method was 5.6 K and 5.2 K for the non-lacunar and Ca-vacancy compound, respectively. The Ca-lacunar La0.5Ca0.5-x xMnO3 (x=0.05) reported in this work demonstrated overall enhancement of the magnetocaloric effect over the LCMO. The technique used to elaborate LCMO materials was beneficial to enhance the magnetocaloric effect and magnetic behaviour. Therefore, we conclude that this less costly environmentally friendly system can be considered as more advantageous candidate for magnetic refrigeration applications then the commonly Gd-based compounds.

cond-mat.mtrl-sci↗

arXiv2019

Built-in electric field induces polarization rotation in bilayer BiFeO3/(Ba,Sr)TiO3 thin films

The crystal structure of BiFeO3/BaxSr1-xTiO3 (BFO/BST) heterostructures with x = 0.2, 0.6 and 0.8, grown on single-crystal MgO (001) substrate was investigated by x-ray diffraction and Raman spectroscopy in order to determine the influence of mismatch-induced strains and spontaneous polarization in BST buffer layers on BFO layers. The lattice parameter of the BFO layers was shown to decrease with increasing concentration of Ba ions, despite the increasing in-plain lattice parameters of tetragonal unit cells of BST layers. The rhombohedral angle of the crystal structure of BFO layers demonstrates an increase towards the ideal cubic perovskite structure with the appearance of the built-in electric field, induced by the spontaneous polarization in buffer layers. This result provides a remarkable tool for the control of polarization in BFO layers and other ferroelectric films in general, by changing the built-in electric field from ferroelectric buffer layer without changing a single crystal substrate.

cond-mat.mtrl-sci↗

arXiv2019

Properties of the low-frequency phonon spectra of ferroelectric barium titanate-based heterostructures

Polarized Raman spectra of the epitaxial Ba0.5Sr0.5TiO3 film, bi-color BaTiO3/Ba0.5Sr0.5TiO3 superlattice, and tri-color BaTiO3/Ba0.5Sr0.5TiO3/SrTiO3 superlattice were studied in a broad temperature range of 80-700 K. Based on the temperature dependence of the polar modes we determined the phase transitions temperatures in the studied heterostructures. In the sub-THz frequency range of the Y(XZ)Y spectra, we revealed the coexistence of the Debye-type central peak and soft mode in bi-color BaTiO3/Ba0.5Sr0.5TiO3 superlattice.

cond-mat.mtrl-sci↗

arXiv2019

Structural, dielectric and magnetic properties of multiferroic (1-x) La0.5Ca0.5MnO3-(x) BaTi0.8Sn0.2O3 laminated composites

High performance lead-free multiferroic composites are desired to replace the lead-based ceramics in multifunctional devices applications. Laminated compounds were prepared from ferroelectric and ferromagnetic materials. In this work, we present laminated ceramics compound by considering the ferromagnetic La0.5Ca0.5MnO3 (LCMO) and the ferroelectric BaTi0.8Sn0.2O3 (BTSO) in two different proportions. Compounds (1-x) LCMO-(x) BTSO with x=1 and 0 (pure materials) were synthesized by the sol gel method and x=0.7 and 0.5 (laminated) compounds were elaborated by welding appropriate mass ratios of each pure material by using the silver paste technique. Structural, dielectric, ferroelectric, microstructure and magnetic characterization were conducted on these samples. X-ray scattering results showed pure perovskite phases confirming the successful formation of both LCMO and BTSO. SEM images evidenced the laminated structure and good quality of the interfaces. The laminated composite materials have demonstrated a multiferroic behavior characterized by the ferroelectric and the ferromagnetic hysteresis loops. Furthermore, the enhancement of the dielectric constant in the laminated composite samples is mainly attributed to the Maxwell-Wagner polarization.

cond-mat.mtrl-sci↗

arXiv2018

Dielectric relaxation and predominance of NSPT and OLPT conduction processes in Ba0.9Sr0.1TiO3

We investigate the relaxation and conduction mechanism of Ba0.90Sr0.10TiO3 (BST) ceramic, synthesized by the solid state reaction method. The dielectric and relaxation properties are analyzed in the temperature range of 380-450°C with alternative current in the frequency range of 20Hz-1MHz. Variation of dielectric constant, ε', with temperature shows a normal ferroelectric transition at Tc=95°C with a weak degree of diffuseness. The modified Cole-Cole equation is used to describe all contributions to the relaxation mechanism. The frequency exponent m(ω,T) deduced from experimental data of the dielectric loss (ε") as m(ω, T)=($\partial$ ln ε"/$\partial$ ln ω) shows a temperature and frequency dependence. Two conduction process are observed: non-overlapping small-polaron tunneling (NSPT) at low frequencies and overlapping large polaron tunneling (OLPT) at high frequencies. The analysis of Nyquist plots reveals also the presence of two contributions, who which the activation energies have been calculated.

cond-mat.mtrl-sci↗