Hysteresis Loop Measurements Research Articles

Design and Experimental Characterization of a Microfluidic Piezoelectric Pump Utilizing P(VDF-TrFE) Film

Advancements in wearable technology and lab-on-chip devices necessitate improved integrated microflow pumps with lower driving voltages. This study examines a piezoelectric pump using a flexible β-phase copolymer poly(vinylidene fluoride-trifluoroethylene) (P(VDF-TrFE)) film. Six samples (S1–S6) were fabricated and subjected to a three-step annealing process to optimize their properties. Characterization was conducted via atomic force microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, impedance analysis, and polarization hysteresis loop measurements. The results show that annealing at approximately 135 degrees Celsius produces a β-phase structure with uniform “rice grain”-like crystallites. A microfluidic pump with a nozzle/diffuser structure, using S4 film as the drive layer, was designed and manufactured. Diaphragm deformation and pump performance were assessed, showing a maximum water flow rate of 25 µL/min at 60 Hz with a peak-to-peak voltage (Vpp) of 60 V. The flow rate could be precisely controlled within 0–25 µL/min by adjusting the Vpp and frequency. This study effectively reduced the driving voltage of the piezoelectric pump, showing that it has significant implications for smart wearable devices.

Investigation of Structural, Elastic and Magnetic Properties of CoCr2-xZrxO4 Nanoparticles.

This study investigates the impact of zirconium substitution on the structural, elastic and magnetic properties of CoCr2O4 nanoparticles. A series of CoCr2-xZrxO4 nanoparticles, x = 0.00, 0.05, 0.10, 0.15 and 0.20, are synthesized via the co-precipitation method. X-ray diffraction (XRD) patterns affirm the formation of single-phase cubic structure with the space group Fd3m. Special attention is given to accurately calculating the average crystallite size (D) and lattice parameter (a) using Williamson-Hall (W-H) analysis and the Nelson-Riley (N-R) extrapolation function, respectively. The increase in Zr4+ content leads to a reduction in crystallite size and an increase in the lattice parameter. Elastic properties are estimated from force constants and the lattice constant, determined from FTIR and XRD, respectively. The observed changes in the elastic constants are attributed to the strength of interatomic bonding. The stiffness constants decrease, while Poisson's ratio increases with increasing Zr4+ content, reflecting the increase in the ductility of the prepared samples. As the Zr4+ content increases, the stiffness constants decrease, and Poisson's ratio increases, reflecting enhanced ductility of the samples. Furthermore, as Zr4+ content rises, Young's modulus, the rigidity modulus and Debye temperature decrease. The magnetic hysteresis loop measurements are carried out at room temperature using a vibrating sample magnetometer (VSM) over a field range of 25 kg. Unsubstituted CoCr2O4 exhibits ferrimagnetic behavior. As Zr4+ content increases, saturation magnetization (Ms) and magnetic moment decrease, while remanent magnetization (Mr) and coercivity (Hc) initially decrease up to x = 0.10, then increase with further increases in x. The novel key of this study is how Zr4+ substitution in CoCr2O4 nanoparticles can effectively modify their elastic moduli and magnetic properties, making them suitable for various applications such as flexible electronics, protective coatings, energy storage components and biomedical implants.

Chemical synthesis, structural and magnetic properties of Al-doped neodymium orthoferrite

Crystalline and single phase of Al doped orthoferrite with stoichiometry NdFe1-xAlxO3 was synthesized by a hydrothermal method. The effect of Al doping on the structure features was investigated by powder X-ray diffraction (PXRD) technique. In this sense, Rietveld refinement was applied in refining the PXRD data. Scanning electron microscopy (SEM) was used to characterize the morphology. And from image analyses show a sub-micron particle size distributions for all samples. Using hydrothermal synthesis method, a micro-sized particle distribution is reached. Measurement of magnetic hysteresis loops showed that the highest coercivity (Hc) obtained was 5.2 kOe for the sample with x=2. Compared to previous results using sol-gel synthesis, the hydrothermal method used in this study showed improved magnetization properties.

Perpendicular magnetic anisotropy and Gilbert damping of MgO/Co100–x Fe x /Pt trilayers

Perpendicular magnetic anisotropy and Gilbert damping of MgO/Co100–x Fe x /Pt (x = 20, 50) trilayers before and after annealing at 200–400 °C were evaluated by hysteresis loop and time-resolved magneto-optical Kerr effect (TRMOKE) measurements. The anisotropy field of the trilayers increased with reducing the CoFe thickness, which reflects the anisotropy is originated from the interface. The annealing around 300 °C was effective to increase the anisotropy because the roughness of the MgO/CoFe interface was reduced by annealing. The effective Gilbert damping α eff also increased with reducing CoFe thickness and increasing annealing temperature. The increase of α eff was considered to be promoted by the interdiffusion between CoFe and Pt after annealing. Small α eff and large perpendicular anisotropy were confirmed to be obtained using Co50Fe50 compared to using Co80Fe20.

Mapping Sliding Ferroelectricity in Bulk (PbS)1.11VS2 Crystals

The recent discovery of sliding ferroelectricity opens up the field of 2D ferroelectricity. However, the limitation to switching the polarization due to the topological protection of the domain walls limits the potential of these heterostructures. Here, the switching of sliding ferroelectric bulk misfit layer compound (PbS)1.11VS2 crystals is studied using switching spectroscopy piezoresponse force microscopy. A large number of measured hysteresis loops can be efficiently analyzed using unsupervised machine‐learning tools. Different switching behavior of the domains is observed on different types of domain structures, and it is shown that full domain switching can be observed for the right type of dislocation structure in the PbS layer.

Martensitic phase mechanism of ternary FeCrMn thin films influenced by the substrate rotation speeds: structural and magnetic properties

In order to investigate the martensitic phase mechanism of the ternary FeCrMn thin films sputtered under the effect of substrate rotation speeds, the structural and related magnetic properties were studied. A range of thin films were deposited at varying rotational speeds of 0, 15, 30, and 45 rpm on flexible amorphous polymer substrates through the use of DC magnetron sputtering. The films were 50 nm thick and were produced at 0.09 nm s−1. The crystal structures showed that all films have a mixture of the body-centred tetragonal (bct) and tetragonal structure. The peak intensity of bct (110) martensitic α’phase increased with the increase of the rotation speeds whereas the tetragonal (430) and (333) peaks stayed almost stable. And, the morphologic surface analysis displayed that the smooth surface turned into a rough surface with the increase of the rotation speeds. After the measurements of hysteresis loops, the films obtained by sputtering of austenitic target have ferromagnetic character with increasing saturation magnetization, MS and coercivity, HC as the substrate rotation speeds increase. With increasing rotation speeds, the increase of the MS from 148 to 242 emu cm−3 and the rise of the HC of the films from 21 to 185 Oe might be explained by the increase of the grain sizes with the increase of % martensitic α’phase caused by increasing rotation speeds. The ternary FeCrMn thin films exhibit increasing % martensitic α’phase and corresponding ferromagnetic properties with increasing substrate rotation speeds. It is concluded that the nanostructured films of FeCrMn have different properties from those of their bulk counterparts under the influence of substrate rotation speeds. Therefore, the martensitic mechanism of the films can easily be controlled by changing rotation speed for potentially flexible new device applications such as spintronics, magnetic hetero-structures, magnetic separators, etc.

Unveiling the Nanoscale Dielectric Gap and Its Influence on Ferroelectric Polarization Switching in Scanning Probe Microscopy

AbstractThe dielectric gap between the scanning probe microscopy (SPM) tip and the surface of a ferroelectric using conductive atomic force microscopy and piezoresponse force microscopy (PFM) is investigated. While the gap functions as a dielectric layer, it also allows tunneling current to inject charges into the ferroelectric when a critical loading force between 10–20 µN is applied to a tip with a radius of 25 nm under a bias voltage of 0.5 V. It is observed that the permittivity of the dielectric gap determines the coercive voltage measured by the piezoresponse hysteresis loop. While such studies done in air often produce coercive voltages much larger than those studied for the same materials in capacitor‐based studies, the use of high permittivity media such as water (ɛr = 79) or silicone oil (ɛr = 2.1‐2.8) produces coercive fields that more closely match those measured in conventional capacitor‐based polarization hysteresis loop measurements. Furthermore, using water as a dielectric medium in PFM imaging enhances the accuracy in extracting the amplitude and phase data from periodically poled lithium niobate crystals. These findings provide insight into the nanoscale phenomena of polarization switching instigated by the SPM tip and provide a pathway to improved quantitative studies.

Influence of GO content on the optical, magnetic and dielectric properties of the BaFe12O19/GO nanocomposites

In this research, BaFe12O19/GO (GO:10, 20, 40, and 50 wt%) nanocomposites were synthesized by sol–gel auto combustion method and their structural, optical, magnetic and dielectric properties were investigated. The x-ray diffraction results for all nanocomposites validate the formation of a hexagonal phase of Ba hexaferrite. The crystallite size decreased with incorporation of graphene oxide (GO) in the hexaferrite phase and making the nanocomposites. In the FESEM analysis, a change in the surface morphology was observed with an increase in the percentage of GO for samples BFO-40GO and BFO-50GO. The band gap energy of the nanocomposites decreased with increasing the amount of the graphene oxide. Measurements of the magnetic hysteresis loop for all nanocomposites were conducted using a vibrating sample magnetometer at room temperature. By increasing the percentage of GO, a decrease in the saturation magnetization was observed for the samples. A decrease in dielectric constant and loss function were also detected at low frequencies when the GO continent goes up. The nanocomposite sample of BFO-40GO exhibited the highest observed value for real part of the Modulus.

Magnetic Properties of Gd-Doped Bi7Fe3Ti3O21 Aurivillius-Type Ceramics.

The magnetic properties of Aurivillius-phase Bi7Fe3Ti3O21 (BFT) and Bi7-xGdxFe3Ti3O21, where x = 0.2, 0.4, and 0.6 (BGFT), were investigated. Ceramic material undoped (BGF) and doped with Gd3+ ions were prepared by conventional solid-state reaction. In order to confirm that the obtained materials belong to Aurivillius structures, XRD tests were performed. The XRD results confirmed that both the undoped and the gadolinium-doped materials belong to the Aurivillius phases. The qualitative chemical composition of the obtained materials was confirmed based on EDS tests. The temperature dependences of magnetization and magnetic susceptibility were examined for the ceramic material both undoped and doped with Gd3+ ions. The measurements were taken in the temperature range from T = 10 K to T = 300 K. Using Curie's law, the value of the Curie constant was determined, and on its basis, the number of iron ions that take part in magnetic processes was calculated. The value of Curie constant C = 0.266 K, while the concentration of iron ions Fe3+, which influence the magnetic properties of the material, is equal 3.7 mol% (for BFT). Hysteresis loop measurements were also performed at temperatures of T = 10 K, T = 77 K, and T = 300 K. The dependence of magnetization on the magnetic field was described by the Brillouin function, and on its basis, the concentration of Fe3+ ions, which are involved in magnetic properties, was also calculated (3.4 mol% for BFT). Tests showed that the material is characterized by magnetic properties at low temperatures. At room temperature (RT), it has paramagnetic properties. It was also found that Gd3+ ions improve the magnetic properties of tested material.

A Time-Domain Perspective on the Structural and Electronic Response in Epitaxial Ferroelectric Thin Films on Silicon.

This operando study of epitaxial ferroelectric Pb(Zr0.48Ti0.52)O3 capacitors on silicon substrates studies their structural response via synchrotron-based time-resolved X-ray diffraction during hysteresis-loop measurements in the 2-200 kHz range. At high frequencies, the polarization hysteresis loop is rounded and the classical butterfly-like strain hysteresis acquires a flat dumbbell shape. We explain these observations from a time-domain perspective: The polarization and structural motion within the unit cell are coupled to the strain by the piezoelectric effect and limited by domain wall velocity. The solution of this coupled oscillator system is derived experimentally from the simultaneously measured electronic and structural data. The driving stress σFE(t) is calculated as the product of the measured voltage U(t) and polarization P(t). Unlike the electrical variables, σFE(t) and η(t) of the ferroelectric oscillate at twice the frequency of the applied electrical field. We model the measured frequency-dependent phase shift between η(t) and σFE(t).

Ferroelectricity‐Induced Surface Ferromagnetism in Core–Shell Magnetoelectric Nanoparticles

Magnetoelectric nanoparticles (NPs) present an important class of nanomaterials with a wide interest in piezocatalytic and biomedical applications. Herein, the results of magnetoelectric and magnetization measurements performed on core–shell NPs having magnetic core (MnFe2O4, MFO) and ferroelectric shell (Ba0.85Ca0.15Ti0.5Zr0.5O3, BCZT) synthesized by the microwave hydrothermal method are reported. Magnetic results are compared with the measurements on reference MFO NPs prepared under identical conditions. Detailed SQUID magnetometer measurements of the magnetization hysteresis loops M(H) down to 2 K reveal the existence of a clear exchange bias effect in pure MFO NPs attributed to the coexistence of ferromagnetic and antiferromagnetic short‐range interactions. When the magnetic core is covered by the thin ferroelectric BCZT shell, it is observed that 1) the shell suppresses the apparent bias effect and 2) induces an “extra” ferromagnetic magnetization at T < 20 K. The results indicate that this “extra” ferromagnetism has a 2D character and it is most likely related to the interface interactions between the MFO core and BCZT shell. Ferroelectric properties and strong magnetoelectric effect in core–shell NPs are revealed via piezoresponse force microscopy under magnetic field. The mechanisms of the observed effects are discussed.

Magnetization reversal process in flat and patterned exchange-biased CoO/[Co/Pd] thin films

Nanostructured magnetic materials have gained great interest due to their possible technological applications in electronic and spintronic devices or in medicine as drug carriers. The key issue which decides on their potential industrial utilization is an exhibited type of a magnetization reversal process. Two main approaches used to describe the switching mechanism are the domain wall motion and coherent magnetization rotation, known as the Kondorsky and Stoner–Wohlfarth models, respectively. The reversal modes can be distinguished by angular measurements of hysteresis loops; however, in many experimental reports the dependencies do not precisely follow either of the models. This makes the question of how the magnetization reversal takes place and how to control or modify it one of the unclear and worth investigation issues in the research on magnetic materials. In this paper, we present our studies on the magnetization reversal in the exchange-biased CoO/[Co/Pd] thin films deposited on a flat substrate and on an array of anodized titanium oxide nanostructures. We studied the reversal mechanism using hysteresis loops and First-Order Reversal Curves. Interestingly, instead of the typical for the flat Co/Pd multilayers Kondorsky process, the system shows a crossover between the domain wall motion and the coherent rotation. A similar situation takes place for the pattern sample. Here, we connect this unusual behavior with the interface exchange interaction responsible for the exchange bias effect.

Strong magnetoelectric coupling in novel Na0.5Bi0.5TiO3–BaFe12-2xCoxTixO19 multiferroic composite

Multiferroic composites of sol-gel synthesized Sodium Bismuth Titanate (Na0.5Bi0.5TiO3) and Co–Ti substituted Barium Hexaferrite (BaFe12-2xCoxTixO19; x = 0.0, 0.5, 1.0, 1.5 and 2.0) in the ratio 3:1 was synthesized through ceramic route. Successful formation of R3c rhombohedral and P63/mmc hexagonal phases corresponding to Na0.5Bi0.5TiO3 and BaFe12-2xCoxTixO19 respectively was confirmed from the XRD and Rietveld refinement pattern. The frequency and temperature dependence of dielectric constant and loss of the composite systems exhibited typical dispersion behaviour which could be understood using the Maxwell-Wagner model. Substituted samples showed enhanced dielectric behaviour where dielectric constant was observed to increase while loss tangent decreased. Using the Universal Jonscher's Power law (JPL), conductivition mechanisms of the composite systems were studied from the ac conductivity behaviour which revealed that the x = 0.0 sample followed Non-overlapping Small Polaron Tunnelling (NSPT) model while the remaining samples followed the Correlated Barrier Hopping (CBH) model. The complex impedance and Nyquist plot analysis showed the enhancement of resistive property in the x≠0 systems. Magnetic hysteresis loop measurements were conducted, and the associated parameters were determined with the assistance of the Law of Approach to Saturation (LAS). Favourable reduction in the magnetic anisotropy was observed indicating the disturbance of magnetic spin structure in the hexaferrite phase. The P-E loops established the novel room temperature multiferroic nature of the composite systems. Significant magnetoelectric coupling was detected at room temperature in all samples, with the x = 0.5 sample exhibiting the highest value of approximately 59.81 mV/cmOe. These desirable properties suggest that the composites may find future device applications as in magnetically tunable energy harvesting devices and self-powered magnetoelectric sensors in the future.

Annealing temperature effects on microstructure and magnetic properties of Fe-6.5wt. %Si alloy strips prepared by TSTRC process

The Fe-6.5wt.%Si alloy exhibits remarkable soft magnetic characteristics, such as high magnetic permeability, low coercivity, high resistivity, and nearly zero magnetostriction. These attributes establish it as an ideal material for low-power, low-noise electric motors and transformers. This investigation aimed to assess the impact of annealing temperature (ranging from 800 to 1200 °C for 1 h) on the microstructure, texture, and magnetic properties of a 0.15 mm thick Fe-6.5wt.%Si alloy sheet, which was obtained by subjecting the strips produced through the top side-pouring twin-roll casting (TSTRC) process to multi-pass warm rolling in the temperature range of 600 ∼ 800 °C, avoiding hot rolling. Additionally, the recrystallization mechanism of the annealed sheet at 1100 °C for 1 h was explored. The findings indicate that enhancing the annealing temperature corresponded to a reduction in magnetic induction (B8 and B50) as well as iron losses (P10/50, P10/400, and P2/1000). The annealed sheet at 1200 °C for 1 h demonstrated the most favorable magnetic properties, displaying iron losses of 0.486 W/kg, 6.895 W/kg, and 1.232 W/kg for P10/50, P10/400, and P2/1000, respectively. These results illustrate excellent overall magnetic characteristics. The coercivity (Hc) of both B8 and B50 decreased as the annealing temperature increased in the hysteresis loop measurements. Specifically, for B8, it decreased from 62.84 A/m to 24.50 A/m, and for B50, it decreased from 78.10 A/m to 35.50 A/m. The average grain size of the samples gradually increased as the annealing temperature ranged from 800 to 1200 °C. The dominant texture observed was {111}, and the volume fraction of {111} texture increased while the volume fractions of {100} and {110} textures decreased. Upon annealing at 1100 °C for 8 s, the elongated and flattened deformed structures were mainly replaced by equiaxed grains, indicating the completion of the recrystallization process. However, there was a noticeable distinction in the coarsening degree of equiaxed grains based on their orientations. The presence of λ-oriented grains was less prominent, while α-oriented and γ-oriented grains were relatively more abundant. As the annealing time increased from 8 s to 1 h, there was a decrease in the presence of λ-oriented and α-oriented grains, while the presence of γ-oriented grains significantly increased.

Ferroelectric Organic-Inorganic Hybrid Ammonium Halogenobismuthate(III) for Piezoelectric Energy Harvesting.

Halogenobismuthate(III) compounds are of recent interest because of their low toxicity and distinct electrical properties. The utility of these materials as ferroelectrics for piezoelectric energy harvesters is still in its early stages. Herein, we report a hybrid ammonium halogenobismuthate(III) [BPBrDMA]2·[BiBr5], crystallizing in a ferroelectrically active polar noncentrosymmetric Pna21 space group. Its noncentrosymmetric structure was confirmed by the detection of the second harmonic generation response. The ferroelectric P-E hysteresis loop measurements on the thin film sample of [BPBrDMA]2·[BiBr5] gave a saturation polarization (Ps) of 5.72 μC cm-2. The piezoresponse force microscopy analysis confirmed its ferroelectric and piezoelectric nature, showing characteristic domain structures and signature hysteresis and butterfly loops. The piezoelectric energy harvesting attributes of [BPBrDMA]2·[BiBr5] were further probed on its polylactic acid (PLA) composites. The 15 wt % [BPBrDMA]2·[BiBr5]-PLA polymer composite resulted in a high output voltage of 26.2 V and power density of 15.47 μW cm-2. The energy harvested from this device was further utilized for charging a 10 μF capacitor within 3 min.

Exploring the supercapacitive potential of Sm3+ doped CoFe2O4 nanoparticles: Enhanced magnetic and dielectric properties

This study investigates the impact of Sm3+ substitution on the structural, electrical, magnetic, and electrochemical properties of CoFe2O4 nanoparticles prepared via a combined solid-state reaction and mechanical milling approach. Rietveld refinement analysis confirms the presence of single-phase cubic spinel structures within the Fd3m space group for both CoFe2O4 (CF) and Co0.95Sm0.05Fe2O4 (SmCF). Field emission scanning electron microscopy and energy dispersive spectroscopy are employed to validate the microstructure and elemental composition. Tauc plot analysis reveals a decrease in the band gap from 2.24 eV for CF to 2.07 eV for SmCF. Hysteresis loop measurements demonstrate an enhancement in saturation magnetization, remanent magnetization, and magnetic moment for SmCF, indicating improved magnetic properties. Furthermore, a substantial increase in magneto-crystalline anisotropy is observed with Sm³⁺ doping. Frequency-dependent dielectric properties are investigated using Havriliak–Negami fitting, confirming the presence of Cole-Cole dispersion. A direct correlation between the dielectric constant and temperature is identified, suggesting higher temperatures lead to elevated values. Notably, the incorporation of Sm³⁺ results in a significant enhancement in specific capacitance, positioning SmCF as a promising candidate for energy storage applications, particularly in supercapacitors.

Realization of ferroelectricity in sputtered Al1-xScxN films with a wide range of Sc content

The ferroelectric properties of wurtzite-structured Al1-xScxN thin films are affected simultaneously by the Sc concentration and in-plane stress state, however, the interaction between these two factors remains unclear. In this work, a series of Al1-xScxN films were deposited on (111) Si substrate by dual-target co-sputtering. X-ray diffraction analyses show the films with a wide range of Sc content (x= 0.05–0.50) have the (0002)-textured wurtzite structure and are in compressive stress state. Ferroelectricity in all the films is confirmed by polarization hysteresis loop measurements at room temperature, and the coercive field exhibits an interesting non-monotonic transition due to the competition between in-plane stress and Sc incorporation. The results provide insight into the wurtzite-structure stability and the nature of ferroelectricity for Al1-xScxN thin films.

Vibration response of in-vacuo tuneable structured fabrics

This paper presents a first survey on the vibration response of beam-like specimens formed by a vacuum plastic bag with single-layer or double-layer 3D-printed structured fabrics encompassing spherical-octahedra, octahedra and cubes truss-like rigid elements. The study reports a comprehensive analysis of the bending stiffness and energy dissipation properties with respect to the level of vacuum as well as the type and number (single or double) of overlapped fabrics. In this context, it first presents a quasi-static analysis of the bending stiffness and energy dissipation of the specimens. Then, it provides a comprehensive overview of the specimens dynamic properties with respect to measurements of the dynamic stiffness frequency response function and with reference to measurements of hysteresis loops at three characteristic frequencies, namely below, at and above the fundamental bending resonance frequency of the beam-like specimens. The study shows that the bending stiffness and thus the fundamental bending resonance frequency of the specimens can be suitably varied by increasing the level of vacuum in the bags. The specimens made with cubic mails show the highest bending stiffness and fundamental resonance frequency. Also, the specimens with double layer mails show much higher bending stiffness and fundamental resonance frequency. The level of vacuum has little effect on the energy loss, which, in general, is characterised by rather low loss factors. This suggests that once the fabric jams, there is little friction between the particles and the principal damping mechanism is offered by the material energy dissipation in the unit particles.

Recapitulation of the magnetic and magnetodielectric properties of (1-x)LiNbO3 - (x)La0.9Na0.1MnO3 (x = 0.1, 0.2, 0.3) composites

The present study provides structural, ferroelectric, magnetic, magnetodielectric and the optical properties of the composite (1-x)LiNbO3-(x)La 0.9Na 0.1MnO3 with different values of x (where x = 0.1, 0.2 and 0.3) at room temperature. Ferroelectric phase LiNbO3(LNB) and magnetic phase La 0.9Na 0.1MnO3(LNMO) were synthesized by conventional solid state reaction method. Rietveld X-ray diffraction pattern reveals the structural purity of the synthesized samples. The ferroic and antiferroic nature of the composites were investigated from M-H hysteresis loop, at x = 0.3 shows highest value of saturation magnetization. The reduced ferroelectric nature of the prepared samples was revealed through P-E hysteresis loop measurement with sample x = 0.1 shows highest value of remnant polarization room temperature. Magnetoelectric coupling nature of the composite sample was confirmed through magnetodielectric measurement. Among the studied composites highest value of magnetodielectric percentage (MD%) at 1 kHz is obtained for sample with x = 0.3. Enhanced magnetodielectric coupling coefficient value of 5.5 is achieved for the sample with x = 0.3. Optical properties were examined from UV absorbance analysis technique. On increasing LNMO content, there was a slight decrease in the band gap energy. The enhanced magnetoelectric coupling property of the present synthesized composite paves the way for more room temperature multifunctional materials.

Low-dimensional halide perovskite/PVDF nanocomposite with enhanced piezoelectricity as flexible biomechanical energy harvester

Sustainable energy harvesting is the need of the hour, and piezoelectric nanogenerators (PENG) offer tremendous opportunities in this field. We have investigated the mechanical energy harvesting applications of a nanocomposite comprising a low-dimensional halide perovskite (HP) and polyvinylidene fluoride (PVDF). Cs4PbBr6 HP was prepared using mechanochemical synthesis, and a composite film of PVDF with Cs4PbBr6 was utilized as the PENG to scavenge energy from day-to-day human biomechanical activities. The properties and output results of the fabricated devices with changing weight percentages (wt.%) of HP used as nanofillers in the PVDF matrix are compared to those of a pure PVDF. A 6 wt.% concentration of Cs4PbBr6 induces the composite's electroactive β-phase to around 87%. The polarization hysteresis (P-E) loop measurement reveals a remanent polarization of 0.31 µC/cm2. The measured piezoelectric coefficient (d33) is about ⁓12 pm/V, and the piezoelectric amplitude is ∼500 pm for the optimized PENG at the maximum applied bias of ±30 V. The device shows an instantaneous output voltage of ⁓90 V, a current of ⁓3.8 μA, and power of ⁓80 µW across a 5 MΩ resistor. Simple daily human activities like finger tapping, leg-toe pressing, finger bending, heel pressing, and walking are used to generate output voltages using PENG with prospective usage in powering portable electronic devices. The output AC voltage of the device is employed to charge a 10 µF capacitor up to ∼3.5 V and shows exceptional stability over long cycles. The output power generated is adequate for lighting commercial LEDs without any external input. The Cs4PbBr6/PVDF composite films thus demonstrate significant potential to be deployed as high-performance, portable, and wearable mechanical energy harvesting devices.