Jacem Zidani

This paper investigates the synthesis and characterization of eco-friendly piezoelectric composite thin films composed of chitosan and Ln₂O₃-doped Na_0.5Bi_0.5TiO₃-BaTiO₃ (NBT-BT) nanoparticles. The films were fabricated using a solution-casting technique, successfully embedding the particles into the chitosan matrix, which resulted in enhanced piezoelectric properties compared to pure chitosan. Characterization methods, such as photoluminescence spectroscopy and piezo-response force microscopy (PFM) which revealed strong electromechanical responses, with notable improvements in piezoelectric performance due to the inclusion of NBT-BT nanoparticles. X-ray diffraction (XRD) analysis revealed a pure perovskite phase with the space group R3c for NBT-BT and NBT-BT-Ln particles. Scanning electron microscopy (SEM) images showed a non-uniform distribution of NBT-BT particles within the chitosan matrix. The results also suggest that the incorporation of rare earth elements further enhances the electrical and piezoelectric properties of the composites, highlighting their potential in flexible and smart device applications. Overall, these findings underscore the potential of chitosan-based composites in addressing environmental concerns while offering effective solutions for energy harvesting and biomedical applications.

The beneficial effects of lanthanide incorporation into 0.94Na_0.5Bi_0.5TiO₃-0.06BaTiO₃ (BNT-BT) matrix on its functional properties were investigated. The conventional solid-state method was used for synthesizing samples. The structural refinement revealed that all samples crystallized in R3c rhombohedral symmetry. Raman spectroscopy study was carried out using green laser excitation and revealed that no clear perceptible variation in frequency is observed. Dielectric measurements unveiled that the introduction of rare earth obstructed the depolarization temperature promoted in BNT-BT, the diffusive phase transition decreasing with increasing lanthanide size. Only dysprosium addition showed comparable diffusion constant and dielectric behavior as the unmodified composition. Further, the comparison of the obtained ferroelectric hysteresis and strain-electric field loops revealed that only Dy-phase exhibited interesting properties comparing parent composition. In addition, the incorporation of lanthanides Ln³⁺ into the BNT-BT matrix led to the development of luminescence characteristics in the visible and near infrared regions, depending on the excitation wavelengths. The simultaneous occurrence of photoluminescence and ferroelectric/piezoelectric properties opens up possibilities for BNT-BT-Ln to exhibit multifunctionality in a wide range of applications.

The beneficial effects of Lanthanide incorporation into 0.94Na0.5Bi0.5TiO3-0.06BaTiO3 (BNT-BT) matrix on its functional properties were investigated. The conventional solid-state method was used for synthesizing samples. The structural refinement revealed that all samples crystallized in R3c rhombohedral symmetry. Raman spectroscopy study was carried out using green laser excitation and revealed that no clear perceptible variation in frequency is observed. Dielectric measurements unveiled that the introduction of rare earth obstructed the depolarization temperature promoted in BNT-BT with decreasing the diffusive phase transition with increasing the lanthanide size. Only Dysprosium addition showed comparable diffusion constant and dielectric behavior as the unmodified composition. Further, the comparison of the obtained ferroelectric hysteresis and strain-electric field loops revealed that only Dy-phase exhibited interesting properties comparing parent composition. In addition, the incorporation of lanthanides Ln3+ into the BNT-BT matrix led to the development of luminescence characteristics in the visible and near infrared regions, depending on the excitation wavelengths. The simultaneous occurrence of photoluminescence and ferroelectric/piezoelectric properties opens up possibilities for BNT-BT-Ln to exhibit multifunctionality in a wide range of applications.Keywords: Sodium Bismuth Titanate; structural refinement; dielectric properties; ferroelectric properties; piezoelectric properties; Photoluminescence.

The effect of ferromagnetic CaMnO₃ (CMO) addition to structural, magnetic, dielectric, and ferroelectric properties of BiFeO₃ is presented. X-ray diffraction and Raman investigation allowed the identification of a single pseudocubic perovskite structure. The magnetic measurement showed that the prepared films exhibit a ferromagnetic behavior at a low temperature with both coercive field and remnant magnetization increased with increasing CMO content. However, a deterioration of magnetization was observed at room temperature. Ferroelectric study revealed an antiferroelectric-like behavior with a pinched P–E hysteresis loop for 5% CMO doping BFO, resulting in low remnant polarization and double hysteresis loops. Whereas, high remnant polarization and coercive field with a likely square hysteresis loop are obtained for 10% CMO addition. Furthermore, a bipolar resistive switching behavior with a threshold voltage of about 1.8 V is observed for high doped film that can be linked to the ferroelectric polarization switching.

The effect of ferromagnetic CaMnO3 (CMO) addition on structural, magnetic, dielectric, and ferroelec-tric properties of BiFeO3 are presented. X ray diffraction and Raman investigation allowed the identifi-cation of single pseudo cubic perovskite structure. The magnetic measurement showed that the pre-pared films exhibit a ferromagnetic behavior at low temperature with both coercive field and remnant magnetization increased with increasing CMO content. However, a deterioration of magnetization was observed at room temperature. Ferroelectric study revealed an antiferroelectric like behavior with a pinched P-E hysteresis loop for 5%CMO doping BFO resulting in low remnant polarization and double hysteresis loops. Whereas, high remnant polarization and coercive field with a likely square hysteresis loop are obtained for 10 % CMO addition. Furthermore, a bipolar resistive switching behavior with a threshold voltage of about 1.8V is observed for high doped film that can be linked to the ferroelectric polarization switching.

The purpose of this research work was to synthesis bioderived nanocomposite films by incorporating Na_0.5Bi_0.5TiO₃ (NBTO) nanoparticles into a chitosan matrix. The NBTO nanoparticles were synthesized using a traditional solid-state technique. Then, through a solution-casting approach, flexible composite films were fabricated using chitosan polymer. The study presents a range of compelling findings. For structural and morphological insights, scanning electron microscopy (SEM) reveals a fascinating morphology where NBTO nanoparticles are uniformly dispersed and interlocked with other particles, forming interconnected grains with significant interspaces within the chitosan matrix. For the optical properties, the spectral response within the 300–800 nm range is primarily governed by light scattering attributed to NBTO particles with diameter sizes ranging from 100 to 400 nm, as well as the distinctive bandgap exhibited by the NBTO phase. The investigation of dielectric properties demonstrates that composite films exhibit markedly higher dielectric values in comparison to pure chitosan films. It is noteworthy that an increase in the NBTO content results in a corresponding increase in dielectric values, enhancing the versatility of these materials. Local piezoelectric measurements utilizing piezoresponse force microscopy confirm the expected piezoelectric and ferroelectric behavior of NBTO particles when dispersed within the chitosan matrix. This research introduces a novel class of biocompatible nanocomposite materials, combining impressive structural attributes, enhanced dielectric properties, and piezoelectric capabilities. The outcomes of this study hold substantial promise for advanced applications in opto- and piezoelectric technologies, marking a significant advancement in biologically sourced materials with multifunctional properties.

The purpose of this research work was to synthesis bio-derived nanocomposite films by incorporating Na0.5Bi0.5TiO3 (NBT) nanoparticles into Chitosan matrix. The NBT nanoparticles were synthesized using a traditional solid-state technique. Then, through a solution casting approach, flexible composite films were fabricated using Chitosan polymer. The morphology and structural assessments were carried out utilizing scanning electron microscopy (SEM), X-ray diffraction and fourier transform infrared technique. The SEM micrographs showed that NBT nanoparticles were randomly distributed and interconnected with other particles, forming interconnected grains with substantial interspaces within the matrix. The spectral response between 300 and 800 nm of the composites is mainly governed by light scattering of NBT particles with diameter sizes in the 100 - 400 nm range and the bandgap of the NBT phase. The dielectric studies demonstrated that the composite films exhibited higher dielectric values compared to the pure Chitosan film. Besides, the increase of NBT amount was found to increase the dielectric values. Additionally, local piezoelectric measurements reveal the expected piezoelectric and ferroelectric behavior for the NBT particles dispersed into the polymer matrix, as locally probed by Piezoresponse Force Microscopy. The studied system bears interest for advanced biocompatible opto- and piezo-electric materials.