Search Results (131)

Ultrasonically assisted catalysis—also called sonocatalysis—is one of the advanced oxidation processes used for wastewater treatment. It has been shown that using nanoparticles of piezoelectric materials as nanocatalysts in sonocatalysis greatly enhances the catalytic reaction rates, a phenomenon that has been dubbed piezocatalysis. Since both sonocatalysis and piezocatalysis are excited by ultrasonic waves and occur simultaneously, it is challenging to discriminate between these two processes and to quantify the contribution of the material’s piezoelectric properties to the overall catalytic activity. It has been previously reported that the piezoelectric properties of the catalyst nanoparticles can improve their catalytic activities by up to one order of magnitude. In this study, we compare the catalytic activity of nanoparticles of both ferroelectric and paraelectric BaTiO₃, hence piezoelectric and non-piezoelectric BaTiO₃ nanoparticles. BaTiO₃ nanoparticles of two different sizes were synthesized using a microwave-assisted hydrothermal method. After a full characterization by transmission electron microscopy (TEM), X-ray diffraction (XRD), and temperature-dependent Raman spectroscopy, the catalytic activities of the BaTiO₃ nanoparticles were determined by monitoring the time dependence of the optical absorption of a solution containing the model pollutant methyl orange, to which the dispersed piezoelectric BaTiO₃ particles were added as catalysts. The 50 nm nanoparticles were found to have a tetragonal crystal structure and symmetry and to be piezoelectric, while the 10 nm nanoparticles had a cubic crystal structure and symmetry and exhibited no piezoelectricity. This study reveals that non-piezoelectric BaTiO₃ nanoparticles exhibit a moderate catalytic activity for the degradation of methyl orange, similar to that of non-piezoelectric TiO₂ nanoparticles. Furthermore, it also shows that, at room temperature, 90% of the overall catalytic activity of piezoelectric BaTiO₃ nanoparticles is due to piezocatalysis, while the remaining 10% is related to sonocatalysis. Using liquid chromatography coupled to mass spectrometry (LC-MS), possible chemical decomposition pathways of the methyl orange dye have also been suggested. Full article

Barium-doped Lead Zirconate Titanate Pb_0.9Ba_0.1(Zr_0.53Ti_0.47)O₃ films with a (001)-dominant orientation were deposited on bulk silicon (Si) substrates using pulsed laser deposition (PLD). Due to the large electromechanical coupling coefficient (K²) of the P(B)ZT layer and the larger shear modulus of the Si substrate compared to the P(B)ZT film, it is possible to obtain higher-order acoustic-resonant modes (Sezawa mode) with SAW wavelength (λ)–piezoelectric film thickness (h) ratios below h/λ < 0.2. Due to the ferroelectric properties of the P(B)ZT film, the resonator’s performance can be improved by increasing the electric polarization. Consequently, the measured quality (Q) factors can be improved from 50 to 200 and the K² values can be improved from 2 to 5% with the resonance frequency ranging from 275 to 500 MHz. Full article

The contributions of BaTiO₃ as the filler and 3-glycidoxypropyltrimethoxysilane as the binder in the matrices of styrene–ethylene–butylene–styrene are evaluated for extended applications in medicine and dentistry. The determinations of stability are achieved by chemiluminescence (CL) under isothermal and nonisothermal modes, measuring the values of oxidation induction time (OIT) and onset oxidation temperature (OOT), respectively, which characterize the progress of material oxidation. The calculation of activation energies for the progress of oxidation from isothermal CL measurements based on OIT values provides proof of the modification of interaction activity on the polymer/barium titanate interface. The increases in the activation energy values from 80 kJ mol⁻¹ for neat polymer to 83 kJ mol⁻¹ for SEBS/BaTiO₃ 1 wt% and 109 kJ mol⁻¹ for SEBS/BaTiO₃ 1 wt%/GPTMS 1 wt% is evidence of the contribution of silane to the structuration of the polymer surface. The influence of the two compounds, filler and additive, makes possible the extension of oxidation induction temperatures measured at 170 °C from 36 min, displayed by pristine polymer, to 245 min and 278 min for the titanate composites free of silane and in the presence of GPTMS 1 wt%, respectively. Full article

The search for efficient photocatalysts for sustainable hydrogen production has driven growing interest in barium titanate (BaTiO₃)-based materials, particularly through polymorph control, surface engineering, and nonmetal and transition-metal doping. In this work, we provide an atomic-scale understanding of structural modifications in nitrogen-, fluorine-, and rhodium-doped BaTiO₃ using Density Functional Theory (DFT), as well as pristine and fluorine-substituted BaTiO₃ using reactive force-field molecular dynamics (ReaxFF-MD) simulations. DFT results for pristine and doped tetragonal BaTiO₃, as well as pristine hexagonal BaTiO₃, reveal that nitrogen and rhodium substitutions enhance the covalent character of Ti-N and Rh-O bonds and promote the redistribution of electron density, as evidenced by noncovalent interaction (NCI) and critical point (QTAIM) analyses, whereas fluorine substitution leads to more ionic Ti-F bonding. ReaxFF-MD simulations of pristine and fluorine-substituted BaTiO₃ in contact with water molecules demonstrate that fluorine substitution suppresses interfacial O-H bond formation and promotes ordered molecular hydration layers near titanium sites, as reflected in bond statistics and radial distribution functions. This study provides molecular insights into the role of N, F, and Rh doping in BaTiO₃ using DFT, and the role of fluorine doping in BaTiO₃ at the water–solid interface using ReaxFF-MD simulations, demonstrating that this integrated computational approach provides a solid basis for the rational design of next-generation materials for energy-related applications. Direct calculations of photocatalytic activity, charge transfer rates, and ferroelectric polarization effects were not performed in this work and remain important directions for future study. Full article

Polymer–ceramic piezoelectric composites are widely investigated to combine the high piezoelectric performance of ferroelectric ceramics with the flexibility and processability of electroactive polymers. However, achieving enhanced dielectric properties while preserving the intrinsic piezoelectric response of the polymer matrix remains challenging, particularly due to dielectric mismatch between the constituent phases and interfacial effects. In this work, barium titanate (BaTiO₃) loaded poly(vinylidene fluoride-trifluoroethylene) (PVDF-TrFE) nanocomposites were fabricated by solvent casting using polyvinylpyrrolidone (PVP) and polysorbate 80 (PS80) as dispersing agents, aiming to obtain polarizable materials capable of retaining high piezoelectric strain coefficient (d₃₃) values and potentially exploiting the opposite polarity of matrix and filler through tailored poling strategies. Morphological, crystallographic, structural, thermal, thermomechanical, dielectric, and piezoelectric characterizations were performed by SEM/EDXS, XRD, FTIR, DSC, TGA, DMTA, dielectric spectroscopy, and d₃₃ measurements. Both dispersants improved filler dispersion and film densification, increasing the crystalline fraction of the matrix, without altering the relative fraction of β-phase (up to 93%). PVP enabled moderate and stable permittivity enhancement with weak frequency dependence, whereas PS80 introduced an electrically active interfacial contribution that amplified low-frequency permittivity at high filler loadings but made the permittivity more frequency-dependent. The piezoelectric response (between −20 pC/N and −25 pC/N) remained predominantly governed by the polymer phase, suggesting limited polarization played by BaTiO₃. These results underlined the critical role of interfacial electrical properties in designing stable high-performance flexible PVDF-TrFE/BaTiO₃ composites. Full article

Electromagnetic (EM) radiation emitted by various sources can cause malfunctions or damage to other electronic devices. Composite materials are widely used for EM field shielding. This work presents and analyzes the dielectric properties of 3D-printed composites containing carbon nanotubes (CNTs) and barium titanate (BaTiO₃) over a broad frequency range. The analyzed 3D structures included a fully filled plate (PL), a basic honeycomb (BH), a honeycomb with re-entrant auxetic features (HREA), and a hierarchical honeycomb (HH). It was found that the composite material containing 1.8 wt.% CNTs and 20 wt.% BaTiO₃ exhibits the highest absorption coefficient in the frequency range from 25 GHz to 53 GHz for all investigated 3D structures. A high concentration of BaTiO₃ increases dielectric loss and interfacial polarization, while providing a CNT network. The synergy of these mechanisms results in the highest absorption of EM waves in the 25–53 GHz range. Moreover, all samples containing BaTiO₃ inclusions exhibited a distinctive electrical conductivity behavior, attributed to the high complex dielectric permittivity of barium titanate, which enhances interfacial polarization. The highest conductivity and dielectric permittivity values were measured in samples containing 1.8 wt.% CNTs and 10 wt.% BaTiO₃, while a further increase in BaTiO₃ concentration caused a decline in dielectric performance. This effect is due to the dispersion and agglomeration of filler particles in composites with higher BaTiO₃ concentrations. Full article

Ceramic-polymer nanocomposites combine the respective advantages of ceramics and polymers, boasting superior mechanical flexibility, thermal stability, optical transparency, and electrical conductivity, enabling their wide use in cutting-edge fields like medicine, aerospace, optoelectronic devices, and energy storage components. Notably, ceramic-polymer nanocomposites are a promising, widely recognized strategy for developing high-energy-density, low-dielectric-loss, and flexible capacitors, due to the ceramic phase’s intrinsic high dielectric constant, which enhances dielectric capability, and the polymer phase’s high breakdown strength and mechanical flexibility. Ultimately, ceramic-polymer nanocomposites can reach an optimal dielectric performance. In this study, polyvinylidene fluoride (PVDF) was used as the matrix material and barium titanate (BaTiO₃) as the reinforcing phase within the composite structure. The BaTiO₃ ceramic particles were incorporated into PVDF via spin-coating technology, with composite formulations prepared at different concentrations (0.5 wt%, 1.0 wt%, 1.5 wt%, 2.0 wt%, 2.5 wt%, 3.0 wt%). A series of key parameters were measured and compared, such as the dielectric constant, breakdown strength, and energy storage density, of the BT/PVDF nanocomposite. The results indicated that the BT/PVDF nanocomposite with the optimal low BaTiO₃ content demonstrates remarkable performance, achieving a breakdown strength (E_b) of 500 MV/m and an effective energy storage density of 15.5 J/cm³. This represents an improvement over conventional uniformly high-filler films. Full article

In the fabrication of ultrathin multilayer ceramic capacitors (MLCCs), the long-term stability of ceramic slurries is a critical yet often overlooked factor that can significantly influence coating uniformity, interfacial adhesion, and process reproducibility. Despite its industrial importance, the time-dependent evolution of slurry dispersion structures during storage and its direct impact on green sheet properties remain insufficiently understood. This study examined the time-dependent physicochemical evolution of barium titanate (BaTiO₃)-based green sheet slurries, which behave as colloidal gel-like dispersion systems, and their influence on the structural, optical, and interfacial properties of the resulting sheets. Dynamic light scattering revealed progressive yet uniform particle aggregation, while viscosity measurements indicated a gradual ~10% decrease over 960 h, reflecting reduced dispersion stability and progressive weakening of the slurry gel network during extended storage. The slurry, consisting of BaTiO₃ particles, polymeric binders, and plasticizers, forms a three-dimensional transient gel network, in which particle–particle and particle–binder interactions govern rheological behavior. The observed viscosity decrease and turbidity reduction indicate gel network relaxation and partial gel–sol–like transition behavior driven by aggregation. Cross-sectional scanning electron microscopy demonstrated that these changes produced a measurable reduction in final green sheet thickness, despite identical processing conditions. Furthermore, peel tests revealed that interfacial adhesion strength increased with storage time, attributable to localized solid enrichment within the slurry gel matrix and enhanced bonding at the release film interface. The reduced coating thickness also contributed to lower optical haze, reflecting a shortened light-transmission path. Collectively, these findings demonstrate that even moderate aggregation in a ceramic network-forming dispersion system substantially alters coating behavior, adhesion, and optical performance. The results underscore the importance of managing gel-network stability and rheology to ensure reliable green sheet fabrication and storage in MLCC manufacturing. Full article

High-quality BaTiO₃ nanopowders were synthesized via a sol–gel method using butyl titanate and barium serving as precursors. This study systematically investigates the influence of calcination temperature (600–1000 °C) and gel aging time (2–10 h) on the phase evolution and microstructure of the nanoparticles. A pure tetragonal phase with a high tetragonality (c/a ratio of 1.0100) and an average particle size of 140 nm was achieved at 1000 °C. X-ray photoelectron spectroscopy and Ultraviolet–Visible diffuse reflectance spectroscopy analyses revealed that high-temperature calcination induced the formation of oxygen vacancies and Ti³⁺ defects, leading to a narrowing of the optical bandgap from 3.01 eV to 2.98 eV. An optimal aging time of 4 h yielded uniform nanoparticles with a high specific surface area, whereas prolonged aging (>6 h) resulted in the re-emergence of BaCO₃ impurities and severe agglomeration due to the formation of a rigid gel network. This work provides a precise processing window for fabricating high-purity, highly tetragonal BaTiO₃ nanopowders suitable for the next generation of miniaturized electronic devices. Full article

The rising global demand for prosthetic limbs, driven by approximately 185,000 amputations annually in the United States, underscores the need for innovative and cost-efficient solutions. This study explores the integration of hybrid materials, advanced 3D printing techniques, and smart sensing technologies to enhance prosthetic finger production. A Taguchi-based design of experiments (DoE) approach using an L09 orthogonal array was employed to systematically evaluate the effects of infill density, infill pattern, and print speed on the tensile behavior of FDM-printed PLA components. Findings reveal that higher infill densities (90%) and hexagonal patterns significantly enhance yield strength, ultimate tensile strength, and stiffness. Additionally, the rheological properties of polydimethylsiloxane (PDMS) were optimized at various temperatures (30–70 °C), characterizing its viscosity, shear-thinning factors, and stress behaviors for 3D bioprinting of flexible sensors. Barium titanate (BaTiO₃) was incorporated into PDMS to fabricate a flexible tactile sensor, achieving reliable open-circuit voltage readings under applied forces. Structural and functional components of the finger prosthesis were fabricated using FDM, stereolithography (SLA), and extrusion-based bioprinting (EBP) and assembled into a functional prototype. This research demonstrates the feasibility of integrating hybrid materials and advanced printing methodologies to create cost-effective, high-performance prosthetic components with enhanced mechanical properties and embedded sensing capabilities. Full article

Bone regeneration relies on the coordinated interplay between mechanical and biological cues. Piezoelectric composites, capable of converting mechanical strain into electrical signals, offer a promising approach to stimulate osteogenesis. This study aimed to develop and characterize polycaprolactone (PCL) and barium titanate (BaTiO₃) composite scaffolds fabricated through thermally induced phase separation (TIPS), and to systematically evaluate the effects of polymer concentration and ceramic incorporation on scaffold morphology, porosity, mechanical properties, and cytocompatibility were systematically evaluated. The resulting scaffolds exhibited a highly porous, interconnected architecture, with 9% PCL formulation showing the most uniform morphology and consistent mechanical and biological behavior. Incorporation of BaTiO₃ did not alter pore structure or compromise cytocompatibility but slightly enhanced stiffness and surface uniformity. SEM-based image analysis confirmed homogeneous BaTiO₃ dispersion across all formulations. MTT assays and confocal microscopy demonstrated robust pre-osteoblast adhesion and spreading, particularly on denser composite scaffolds, confirming that the inclusion of BaTiO₃ supports a favorable environment for cell proliferation. Overall, optimizing polymer concentration and ceramic dispersion enables fabrication of structurally coherent, cytocompatible scaffolds. The findings establish structure–property–biology relationships that serve as a baseline for future investigations into the electromechanical behavior of PCL/BaTiO₃ scaffolds and their potential to promote osteogenic differentiation under physiological loading. Full article

High-performance piezoelectric poly(vinylidene fluoride) (PVDF) has great application potential in the field of microsensors, but achieving efficient polarization remains a challenge. Here, the in situ doping electrospinning technique is employed to enhance the piezoelectric properties by introducing a single dose of zinc oxide (ZnO) or barium titanate (BaTiO₃,BTO) dopants. The effects of key processing parameters on the morphology of nanofiber membranes were systematically investigated. In addition, the influence of zinc oxide (ZnO) or barium titanate (BTO) dopant concentrations on the piezoelectric properties of PVDF was examined. The microstructure, electrical performance, and β-phase content of the composite membranes were characterized. Results indicate that the composite film with a doping formulation of 16 wt% PVDF and 10 wt% ZnO exhibits optimal overall performance: the β-phase content of PVDF reaches 52.8%, and the output voltage reaches 1.5 V, which is 2.5 times higher than that of the undoped PVDF nanofiber membranes. This study provides an effective doping strategy for the fabrication of high-performance piezoelectric nanofiber membranes. Full article

Although total knee replacements have an insignificant impact on patients’ mobility and quality of life, real-time performance monitoring remains a challenge. Monitoring the load over time can improve surgery outcomes and early detection of mechanical imbalances. Triboelectric nanogenerators (TENGs) present a promising approach as a self-powered sensor for load monitoring in TKR. A TENG was fabricated with dielectric layers consisting of Kapton tape and 3D-printed thermoplastic polyurethane (TPU) matrix incorporating CNT and BTO fillers, separated by an air gap and sandwiched between two copper electrodes. The sensor performance was optimized by varying the concentrations of BTO and CNT to study their effect on the energy-harvesting behavior. The test results demonstrate that the BTO/TPU composite that has 15% BTO achieved the maximum power output of 11.15 μW, corresponding to a power density of 7 mW/m², under a cyclic compressive load of 2100 N at a load resistance of 1200 MΩ, which was the highest power output among all the tested samples. Under a gait load profile, the same TENG sensor generated a power density of 0.8 mW/m² at 900 MΩ. By contrast, all tested CNT/TPU-based TENG produced lower output, where the maximum generated apparent power output was around 8 μW corresponding to a power density of 4.8 mW/m², confirming that using BTO fillers had a more significant impact on TENG performance compared with CNT fillers. Based on our earlier work, this power is sufficient to operate the ADC circuit. Furthermore, we investigated the durability and sensitivity of the 15% BTO/TPU samples, where it was tested under a compressive force of 1000 N for 15,000 cycles, confirming the potential of long-term use inside the TKR. The sensitivity analysis showed values of 37.4 mV/N for axial forces below 800 N and 5.0 mV/N for forces above 800 N. Moreover, dielectric characterization revealed that increasing the BTO concentration improves the dielectric constant while at the same time reducing the dielectric loss, with an optimal 15% BTO concentration exhibiting the most favorable dielectric properties. SEM images for BTO/TPU showed that the 10% and 15% BTO/TPU composites showed better morphological characteristics with lower fabrication defects compared with higher filler concentrations. Our BTO/TPU-based TENG sensor showed robust performance, long-term durability, and efficient energy conversion, supporting its potential for next-generation smart total knee replacements. Full article

Barium strontium titanates (Ba_1−xSr_xTiO₃, BST) with varying barium-to-strontium ratios were synthesized by the solid-state route (SSR) as well as by the sol–gel process (SGP). In the case of the SSR, the strontium amount x was varied from 0.0 to 0.25 in 0.05 steps, due to the enhanced synthetic effort, and in the case of the SGP, x was set only to 0.05, 0.15, and 0.25. The resulting properties after synthesis, calcination, and sintering, like particle size distribution, specific surface area, particle morphology, and crystalline phase were characterized. The expected tetragonal phase, free from any remarkable impurity, was found in all cases, and irrespective of the selected synthesis method. Pressed pellets were used for the measurement of the temperature and frequency-dependent relative permittivity enabling the estimation of the Curie temperatures of all synthesized BSTs. Irrespective of the selected synthesis method, the obtained Curie temperature drops with increasing strontium content to almost identical values, e.g., in the case of x = 0.15, a Curie temperature range 95–105 °C was measured. Thin BST films could be deposited on different substrate materials applying electrophoretic deposition in a good and reliable quality according to the Hamaker equation. The properties of the BSTs obtained by the simpler solid-state route are almost identical to the ones yielded by the more complex sol–gel process. In future, this result allows for a possible wider usage of BST perovskites for ferroelectric and piezoelectric devices due to the easy synthetic access by the solid-state route. Full article

The electrocaloric effect (ECE) has become one of the most intensively studied topics in ferroelectrics, with dozens of new papers that report experimental results and provide increasingly extensive data compilations every year. However, the heterogeneity of the literature, arising from differences in compositions, dopants, preparation routes, measurement protocols, and analysis methods, makes direct comparison between studies highly problematic. In this work, we focus on barium titanate (BaTiO₃) as a representative lead-free ferroelectric system. BaTiO₃ was chosen because, within this class of materials, it offers by far the largest body of reported ECE results, obtained under a wide range of experimental conditions, thus allowing for the most comprehensive characterization. Using this example, we explore whether meaningful patterns related to the influence of chemical substitution on the magnitude and temperature dependence of the ECE can be discerned. In addition, we critically examine why certain comparisons reported in the literature may be misleading or inherently unreliable. Finally, we discuss predictive approaches, including those employing artificial intelligence algorithms, and evaluate their applicability and limitations in modeling the electrocaloric response. Full article