BaTiO3 Content Research Articles

Effect of Synthesis Process on The Piezoelectric Properties of (1-x) NBT-xBT: A Comparative Study Between Solid State and Hydrothermal Methods

Lead-free oxide perovskite materials are produced to ensure that no toxic or dangerous waste is released into the environment, although this technique often requires a high-temperature synthesis method. Nevertheless, the development of an environmentally friendly chemical process to carry out the synthesis of perovskite material in the laboratory at low temperature is a major challenge. In this investigation, to lower the temperature of the thermal treatment, (1-x)(Na0.5Bi0.5)TiO3-xBaTiO3 (abbreviated as (1-x)NBT-xBT) ceramics were synthesized using two different methods: a hydrothermal method and a conventional calcination process (solid-state), using the same reagents. The effects of various synthesis techniques on the composition, structure, morphology, and dielectric properties of the (1-x)NBT-xBT ceramics were registered and examined. The XRD plots taken at ambient temperature were used to verify the phase formation of the samples. The occurrence of functional bands was also verified by Raman spectroscopy at ambient temperature. Using the Rietveld refinement method were able to detect the morphotropic phase boundary (MPB) near x=0.05-0.07. When the hydrothermal process was adopted, the (1-x)NBT-xBT ceramics show a single perovskite structure sintered at 1000°C. Moreover, scanning Electron Microscopy (SEM) examination revealed a uniform distribution of grains and a significant change in grain size with the increase in BaTiO3 concentration when compared to the conventional method. The microstructure of ceramics is generally strongly influenced by the method used to prepare the powders, which has a considerable impact on their performance. Piezoelectric and dielectric properties of the specimens have been compared with the properties of those prepared by the hydrothermal process. Thus, the choice of the suitable synthesis method depends on the desired properties of the (1-x)NBT-xBT materials.

Structural, optical, and morphological properties of PVC-BaTiO3 nanocomposite films

This work aims to fabricate barium titanate (BaTiO3) nanoparticles and study the effect of adding different contents of BaTiO3 nanoparticles on the structural, optical, and electrical properties of PVC polymer matrices. The PVC/BaTiO3 nanocomposite films were characterized by X-ray diffraction, FT-IR spectroscopy, and SEM. In addition, dielectric properties were studied within the frequency range of 0.1 KHz–6 MHZ. The XRD analysis reveals an amorphous nature of pure PVC with two characteristic peaks at 2θ = 17.09° and 2θ = 23.25°, and it reveals that BaTiO3 has sharp and narrow peaks. In PVC/BaTiO3 nanocomposite films, all XRD peaks of BaTiO3 appeared in all the samples with an increase in the average particle size from ∼46 nm to 55 nm. There is no shift of IR position in PVC bands, but the decreased intensity of some bands suggests complexation between PVC and BaTiO3. The UV–visible absorption spectrum of pure PVC has a band at λ = 278 nm. This band was shifted to 252 nm after adding BaTiO3 content. UV–visible transmission spectra demonstrate a decrease in the transmittance as an increase of BaTiO3 content from 89.23 % for pure PVC to 5.23 % for 0.1 wt% of BaTiO3. The values of the optical bandgap decrease with increasing BaTiO3 contents due to defect formation in PVC matrices. The optical parameters of the prepared nanocomposite films were also enhanced. The AC conductivity shows an increase with both frequency and BaTiO3 concentration, leading to enhanced movement of charge carriers and relaxation of interface polarization.

Influence of BaTiO3 substitution on structural and thermal response of lead borosilicate glass for ultrasonic applications

An extensive examination of the impact of BaTiO3 doping on the mechanical and thermal characteristics of lead-borosilicate glasses is provided in this work. The glass density increases noticeably (from 6020 for BaTiO3 to 2533 kg/m3 for SiO2), and the molar volume decreases, suggesting a denser and more compact structural arrangement. The mechanical properties exhibited a notable improvement upon the addition of BaTiO3. Specifically, the longitudinal ultrasonic velocity (VL) increased from 3927 to 4458 m/s, and the shear velocity (VS) increased from 2317 to 2630 m/s, indicating a reinforced glass network. The bulk modulus increased from 35.71 to 58.06 GPa, and Young’s modulus increased from 57.2 to 92.98 GPa. These significant increases in elastic moduli were attributed to tighter atom packing and higher levels of cross-linking within the glass matrix. Furthermore, the glass structure’s increased rigidity and connectedness were further indicated by the Debye temperature (θD), which increased from 296.8 to 347.3 K. The influence of BaTiO3 on the thermal analysis is demonstrated, which revealed that increasing BaTiO3 content raises both the glass transition and crystallization temperatures. The results of the experiment demonstrate how much BaTiO3 doping can improve the physical characteristics of lead-borosilicate glasses, enabling them to be used in sophisticated optical and structural applications.

BaTiO3-B2O3-MgO-Na2O-CaO glass series: Radiation shielding, thermal, and mechanical properties

The effect of BaTiO3 on the mechanical, thermal and radiation shielding properties of the borate glass with the composition of (60-x)B2O3 + 10MgO + 15Na2O + 15CaO+(x)BaTiO3 (x: 0,2.5,5,7.5 and 10 mol%) were synthesized by the melt quenching method. The physical, thermal, mechanical and radiation protection properties of the glasses produced with this designed composition were carefully investigated. As the BaTiO3 amount increased from 0 % to 10 %, the density of the glass increased from 2.571 to 2.870 g/cm3 and the glass thermal stability (ΔT) also enhanced from 51 to 63. The LAC value at 276 keV, 0.2831 cm−1 for 0 % BaTiO3 and enhanced linearly with increasing BaTiO3 concentration and reach to 0.3475 cm−1 at 10 % BaTiO3. The experimentally obtained MAC values are in agreement with the theoretically calculated MAC values with XCOM and MCNP6.2. It was concluded that the increase in the BaTiO3 value of the glass positively affects the radiation shielding properties of the glasses.

3D Printing of Flexible BaTiO3/Polydimethylsiloxane Piezocomposite with Aligned Particles for Enhanced Energy Harvesting.

With the rapid development of human-machine interactions and artificial intelligence, the demand for wearable electronic devices is increasing uncontrollably all over the world; however, an unsustainable power supply for such sensors continues to restrict their applications. In the present work, piezoelectric barium titanate (BaTiO3) ceramic powder with excellent properties was prepared from milled precursors through a solid-state reaction. To fabricate a flexible device, the as-prepared BaTiO3 powder was mixed with polydimethylsiloxane (PDMS) polymer. The BaTiO3/PDMS ink with excellent rheological properties was extruded smoothly by direct ink writing technology (DIW). BaTiO3 particles were aligned due to the shear stress effect during the printing process. Subsequently, the as-printed composite was assembled into a sandwich-type device for effective energy harvesting. It was observed that the maximum output voltage and current of this device reached 68 V and 720 nA, respectively, for a BaTiO3 content of 6 vol %. Therefore, the material extrusion-based three-dimensional (3D) printing technique can be used to prepare flexible piezoelectric composites for efficient energy harvesting.

3D Printed Piezoelectric BaTiO3/Polyhydroxybutyrate Nanocomposite Scaffolds for Bone Tissue Engineering.

Bone defects are a significant health problem worldwide. Novel treatment approaches in the tissue engineering field rely on the use of biomaterial scaffolds to stimulate and guide the regeneration of damaged tissue that cannot repair or regrow spontaneously. This work aimed at developing and characterizing new piezoelectric scaffolds to provide electric bio-signals naturally present in bone and vascular tissues. Mixing and extrusion were used to obtain nanocomposites made of polyhydroxybutyrate (PHB) as a matrix and barium titanate (BaTiO3) nanoparticles as a filler, at BaTiO3/PHB compositions of 5/95, 10/90, 15/85 and 20/80 (w/w%). The morphological, thermal, mechanical and piezoelectric properties of the nanocomposites were studied. Scanning electron microscopy analysis showed good nanoparticle dispersion within the polymer matrix. Considerable increases in the Young's modulus, compressive strength and the piezoelectric coefficient d31 were observed with increasing BaTiO3 content, with d31 = 37 pm/V in 20/80 (w/w%) BaTiO3/PHB. 3D printing was used to produce porous cubic-shaped scaffolds using a 90° lay-down pattern, with pore size ranging in 0.60-0.77 mm and good mechanical stability. Biodegradation tests conducted for 8 weeks in saline solution at 37 °C showed low mass loss (∼4%) for 3D printed scaffolds. The results obtained in terms of piezoelectric, mechanical and chemical properties of the nanocomposite provide a new promising strategy for vascularized bone tissue engineering.

Properties of ferroelectric composites in the microwave range

Ferroelectric ceramics of barium titanate and its solid solutions have found wide applications in technology, while compositions of a binary system with strontium titanate are most in demand. Electrically controlled components based on the barium titanate – strontium titanate ferroelectric ceramics are widely used in accelerator technology and the use of these materials is relevant at the present time. In the microwave range, composites based on the solid solution system barium titanate – strontium titanate ВаxSr1–xTiO3 (BST). Ferroelectric samples based on ВаxSrx–1TiO3 compound, where x = 0; 0.1; 0.3; 0.5; 0.7 were obtained using a conventional ceramic technology. The temperature dependences of the electrical properties of bulk ceramic samples based on ferroelectric composites were received in the temperature range 100°C to 350°C at a frequency of 1 kHz. It has been established that dielectric parameters significantly depend on the BaTiO3 content in BST compositions. To carry out a research in the frequency range from 0.1 to 8.5 GHz, an experimental setup was manufactured for measuring the electrical properties of ferroelectric materials based on an Agilent E5071C vector analyzer and a microstrip line. To conduct temperature studies, a microstrip line with a controlled sample was placed in a heat, cold and moisture chamber of the Bench-Top SU-261 series, in which it has been heated up to 60°C. The amplitude-frequency characteristics of the transmission coefficient (S21) of samples when heated from 20 °C to 60°C with an interval of 10 degrees were studied. The resonant frequency and quality factor of the resonator have been determined from the amplitude-frequency characteristic. Based on the value of the resonant frequency and the geometric dimensions of the sample, the dielectric constant of the sample material was calculated. It has been shown that with increasing barium titanate content (x = 0.1–0.3), the dielectric constant of the samples under study increases, and the resonant frequency shifts to lower frequencies. For samples with a barium titanate content of 50% and higher (x≥0.5), there are no resonance dependences and strong absorption of electromagnetic waves is observed. It has been established that with increasing temperature, the resonant frequency of composite material samples shifts to higher frequencies. Frequency dispersion of the dielectric constant is observed, which indicates the relaxor properties of the ceramic samples under study. Experimental investigations were carried out using a microwave strip line, a coaxial measuring cell and a capacitive converter; this made it possible to measure the dielectric constant of materials with values of more than several hundred in the microwave range and significantly reduce the control time when conducting thermal studies. It was shown that with a change in temperature, the electrophysical properties of the samples change significantly, which can be used in various systems and devices to change the reflection coefficient and phase of the electromagnetic wave.

Energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 thin films on Pt/mica substrates

We investigated the energy storage and ferroelectric properties of flexible 1-x(Na0.5Bi0.5TiO3)-xBaTiO3 (NBT) thin films with BaTiO3 (BT) concentrations ranging from 0 to 6 mol% on Pt/mica substrates depending on the BT concentration. The NBT thin films exhibiting preferentially a-oriented crystallinity on the (111) Pt/mica substrates showed improved leakage current characteristics by increasing the BT concentration. In particular, the NBT thin films with zero BT concentration showed a high remanent polarization of about 28.4 μC/cm2. On the other hand, the NBT thin films with a BT concentration of 6 mol% significantly reduced the remanent polarization to about 4.7 μC/cm2 due to the characteristics of the relaxor. As a result, the NBT thin films with a BT concentration of 6 mol% showed a high energy storage efficiency of 89.5 % with a high recoverable energy storage density of 54.3 J/cm3 and a low loss energy density of 6.3 J/cm3.

Influence of laser intensity and BaTiO3 content on the surface properties of 3YSZ.

Zirconia-based dental implants are in direct contact with living tissues and any improvements in their bioactivity and adhesion to the tissues are highly welcome. In this study, different ratios of barium titanate (BT) were added to 3mol% yttria-stabilized zirconia (3YSZ) through conventional sintering. The laser-texturing technique was also conducted to improve the biological performance of 3YSZ ceramics. The composition and the surface of the prepared composites were characterized by X-ray diffraction and scanning electron microscopy (SEM), respectively. The roughness and surface wettability of the composites were also measured. Furthermore, MC3T3-E1 pre-osteoblast cells were used for the in vitro experiments. Cell viability was evaluated using a commercial resazurin-based method. Morphology and cellular adhesion were observed using SEM. Based on the results, the laser texturing and the barium titanate content influenced the surface characteristics of the prepared composites. The laser-textured 3YSZ/7mol% BT composites showed a lower water contact angle compared to the other samples, which indicated superior surface hydrophilicity. The cell viability and cell adhesion of 3YSZ/BT composites increased with the rise in the barium titanate content and laser power. An elongated cell morphology and apatite nucleation were also observed by the BT content. Overall, the laser-treated 3YSZ/5 and 7mol% BT composites may be promising candidates in hard tissue repair due to their good cell response.

Enhanced high-frequency dielectric properties in ZrO2–BaTiO3 ceramic heterostructures

We report a comprehensive investigation of the high-frequency dielectric properties in (ZrO2)100−x(BaTiO3)x heterostructures, with x ranging from 0 to 100. Modifications in the BaTiO3 content of the composition enables us to tailor the dielectric constant of the resulting ceramic sheets. Rheology, apparent porosity, X-ray diffraction, and Scanning Electron Microscopy were employed to clarify the dielectric behavior of the sheets. The samples achieved highly stable dielectric measurements, with values of ɛ′=4.09 for x=0 and 12.58 for x=100, representing an ɛ′ enhancement of over 200% with the tuning of the structure. The results highlight the successful fabrication of heterostructured ceramic sheets and demonstrate the ability of tailoring the electric, structural, and dielectric properties of both ZrO2 and BaTiO3 materials when acting together. Besides, the evolution of the dielectric constant can be used to handle the material properties according to the needs for specific technological applications.

Exploring the potential of metal-doped perovskite-oxides as oxygen reduction catalyst for enhancing the performance of microbial desalination cells

Microbial desalination cells (MDCs) have been employed for dissolved salts and contaminant removal along with electricity production. Although oxygen depletion is a momentous reaction in the electrochemical energy transformation, its sluggish kinetics prevent it from being accustomed to fuel cells. Oxygen reduction reactions (ORR) in alkaline environments and perovskite oxide catalysts for converting energy electrochemically have emerged as excellent and promising alternatives. Various concentration of Sn-doped oxygen-deficient BaTiO3 was incorporated to study ORR behavior and effect on MDC performance. This perovskite catalyst contains a considerable percentage of cubic BaTiO3 (with 100 nm size) confirmed by material characterization studies. Power density obtained in the absence of the catalyst was 4.7 W/m3 which increased to 6.7 W/m3 upon utilization of BaTiO3 with salt removal of 76.7%. Catalyst loading of 1 mg/cm2 and initial total dissolved solid (TDS) concentration of 20 g/L was found to be effective for improving the desalination rate in MDC. Electrochemical analyses also revealed enhancement in electrocatalytic behavior of cathodic kinetics under such operating conditions. Thus, Sn-doped BaTiO3 catalyst can be a suitable candidate for upscaling of MDC to meet the sustainable development goals.

The Role of Nanocrystallization for the Enhancement of Structural, Electrical, and Transport Properties of BaTiO3-V2O5-PbO Glasses

Glass-ceramic nanocrystals (GCNs) were created via annealing at crystallization temperature Tc for the parent BaTiO3-V2O5-PbO glasses prepared by the melt quenching technique. The amorphous character of the existing quenched glasses was confirmed by scanning electron microscopy. Furthermore, the general characteristics of x-ray diffraction support the amorphous nature of the glasses. In the related heat-treated samples, the typical nanostructure size is less than 60 nm. It was discovered that an increase in the density of the GCNs occurred with an increase in the BaTiO3 percentage. Also, with increasing BaTiO3 content, a slight increase was observed in the crystallization and glass transition temperature from 335°C to 365°C and 265°C to 320°C, respectively. It was revealed that suitable nanocrystallization at temperatures around the onset of Tc for 1 h was able to significantly increase the electronic conductivity of the initial glasses. The accumulation of V4+–V5+ pairs at the interlayer zones created between nanocrystallites and the glassy phase were accountable for electron hopping in the current approach, which was significantly higher than in the glass phase. The experimental findings were investigated in a model based on the “core–shell” idea. Appropriate values for the different small polaron hopping (SPH) variables were found from the best fits. Non-adiabatic hopping of small polarons was responsible for the conduction. As a result of the alteration of the nanostructure, conductivity was enhanced. Compared to the original glasses, the final materials have significantly better electrical conductivity. Such characteristics can be utilized in the design for industrial applications.

Piezoelectric properties of PVDF‐TrFE/BaTiO3 composite foams with different contents of TrFE units

AbstractPiezoelectric (PE) materials play an important role in the emerging field of micro and wearable electronics. Achieving high PE response is a key feature for their use in energy harvesting and sensing systems. In this study, highly porous lightweight composite foams composed of PVDF‐TrFE (70/30 and 80/20 mol%) and different BaTiO3 content (5, 10, and 20 wt%) are prepared by thermally induced phase separation method. The PE foams were structurally and thermally examined by using Fourier‐transform infrared spectroscopy, x‐ray diffraction, differential scanning calorimetry, and thermogravimetric analysis analyses. All composite foams were characterized by high β‐phase content, while the addition of ceramic particles resulted in higher crystallinity and thermal stability of the investigated foams. Two distinct poling methods were employed due to the different molar compositions of the copolymers. The PE response was measured by the PE strain coefficient (d33) and the output current (Ip). The composite foams based on PVDF‐TrFE 70/30 mol% copolymer, having two well‐separated Curie temperatures for the organic and inorganic phases, can be polarized to achieve the contribution of both components to the PE performance, reaching the highest value of −28.3 pC N−1 and 130 nA at 10 Hz for the composite with 20 wt% BaTiO3.

Early stage nanocrystallization as a method of enhancement of electrical properties of lead/barium titanate doped vanadium borate glasses

Glass–ceramic nanocomposites (GCNs) of (10 − x) BaTiO3 (BT)–xPbTiO3 (PT)–60V2O5–30B2O3 with x = 0, 2.5, 5, 7.5 and 10 mol% were formed during heat treatment of conventional melt quenching glasses. X-ray diffraction was used to ensure glass and GCNs formation. Glasses and GCNs densities were measured by Archimedes principle. Fine polar clusters of lead titanate and/or barium titanate incorporation into vanadium borate glass matrix strongly depend on the composition. It was found out that the electrical conductivity of the initial glasses can be considerably improved by proper early stage of nanocrystallization at temperatures approaching the crystallization temperatures determined by DSC method. GCNs show massive increase in electrical conductivity (up to 6 orders of magnitude) as a function of BaTiO3 content. By increasing BaTiO3 content, the activation energy values have been found to increase. The enhancement in electrical conductivity of GCNs can be attributed to the increase in the crystalline phases in the glassy matrix which increases the concentrations of the V ion pairs.

Scalable, flexible BaTiO3/PVDF piezocomposites prepared via supersonic spraying for use in energy harvesting and integrated energy storage devices

Flexible piezoelectric nanogenerators (PENGs) are emerging as sustainable power sources for self-charging wearable electronic devices owing to their ability to harvest ambient mechanical energy. The use of piezopolymer polyvinylidene fluoride (PVDF) and piezoceramic barium titanate (BaTiO3) as flexible composite materials for PENGs deposited using the supersonic cold-spraying technique was investigated in this study. The PENG with an optimized concentration of BaTiO3 to PVDF generated a piezoelectric voltage of 11.5 V when subjected to a tapping force of 5 N for 15,000 cycles. Scanning electron microscopy images captured after cycling confirm the robustness of the BaTiO3 and PVDF composite films. A maximum power of 28.7 μW was achieved at an impedance-matching resistance of 0.7 MΩ. A flexible-PENG bending test of 3000 cycles with a bending radius of 0.8 cm confirmed the durability when an optimal PVDF matrix accommodated well-dispersed BaTiO3 particles. Furthermore, the ferroelectric characteristics of BaTiO3 and PVDF were activated by electrical poling for 14 h, thereby increasing an open circuit voltage to 37.5 V, indicating the possibility of a 3.3-times enhancement after poling.

Photocatalytic dye degradation by BaTiO3/zeolitic imidazolate framework composite

Chemical dyes present in wastewater generated from textile and paint industries can cause serious environmental and health hazards if not adequately treated. Photocatalytic degradation, an eco-friendly water treatment method, utilizes charge carriers generated from sunlight to remove pollutants in water without requiring additional energy input. Since the interaction between polluted water and a catalyst is crucial in water treatment, an emerging technology involves the combination of porous materials and light-sensitive materials. In this study, BaTiO3 nanoparticles are loaded into a Zeolitic Imidazolate Framework (ZIF-8) to create BaTiO3 @ZIF-8 nanocomposites for the photocatalytic degradation of methylene blue (MB) under solar irradiation. To facilitate the smooth transfer of charge carriers between BaTiO3 and ZIF-8, ZIF-8 has been synthesized in the presence of BaTiO3, allowing ZIF-8 to grow on the surface of BaTiO3. The concentration of BaTiO3 is adjusted during synthesis to optimize the photocatalytic performance. Among the different compositions, 25 wt% BaTiO3 @ZIF-8 demonstrates the highest photocatalytic activity. This composite efficiently degrades 93 % of MB dye in 180 min and completely degrades the Congo Red dye in just 75 min under solar irradiation. Furthermore, the photocatalyst exhibits good cyclability over four cycles, maintaining its excellent performance. These results suggest that the current study contributes to the synthesis of highly effective photocatalysts for the breakdown of dyes in aqueous media under sunlight exposure.

High-efficiency energy storage in Nd-doped (1-x)BiFeO3–xBaTiO3 relaxor ferroelectric ceramics

Dielectric capacitors as energy storage electronics have drawn much attention due to ultrahigh power densities with quick charging and discharging rates. In this report, A-site Nd-doped (1-x)BiFeO3-xBaTiO3 (x = 0.2–0.45) relaxor ferroelectric ceramics with superior storage efficiencies were prepared with 0.1 wt% MnO2 additive. Energy-storage efficiency (η) increases from 63.7% to 89% at 190 kV/cm as BaTiO3 increases accompanied by recoverable energy densities (Wrec) in the range of 2.5–2.7 J/cm3. The energy-storage performance persists thermally stable up to 125 °C. The superior storage efficiency is associated with growth of the cubic Pm-3m symmetry and the core-shell structure with increasing BaTiO3 content. The formation of nanocluster/nanomosaic structure also plays an essential role as a barrier in suppressing the long-range polarization order. This work provides a design of binary rare-earth doped BiFeO3–BaTiO3 dielectric ceramics for thermally stable and high-efficiency electrical energy storage.

The Influence of BaTiO3 Content on the Energy Storage Properties of Bi0.5Na0.5TiO3-Bi(Mg2/3Nb1/3)O3 Lead-Free Ceramics

Na0.5Bi0.5TiO3 (NBT)-based ceramics are promising lead-free candidates for energy-storage applications due to their outstanding dielectric and ferroelectric properties derived from large polarization. However, the high coercive field and large remnant polarization are unfavorable for practical applications, and thus NBT-based ceramics with relaxation behavior via doping/forming solid solutions with other elements/components have been widely studied. In this work, BaTiO3 (BT) was introduced to the 0.94Na0.5Bi0.5TiO3-0.06Bi(Mg2/3Nb1/3)O3 system by a conventional solid-state reaction to form a homogeneous solid solution of 0.94[(1−x)Na0.5Bi0.51TiO3-xBaTiO3]-0.06Bi(Mg2/3Nb1/3)O3 (BNT-100xBT-BMN). As the BT content increased, the proportion of the rhombohedral R3c phase increased while that of the tetragonal P4bm phase decreased, leading to the maximum Pmax (38.29 μC/cm2) and Eb (80 kV/cm) obtained in BNT-7BT-BMN (x = 0.07) composition. Specifically, the optimal energy storage properties of Wrec ~ 1.02 J/cm3 and η ~ 62.91% under 80 kV/cm were obtained in BNT-7BT-BMN ceramics, along with good temperature stability up to 200 °C, which are promising factors for future pulse power applications.

Piezoelectric Nanogenerators Based On BaTiO3/PDMS Composites for High-Frequency Applications.

A series of highly flexible and environmentally friendly composites based on polydimethylsiloxane (PDMS) filled with 200 nm size ferroelectric BaTiO3 (BTO) particles at different concentrations (from 7 to 23 vol %) have been fabricated by a simple dispersion method. The dielectric, piezoelectric, and ultrasonic properties have been studied. The ferroelectric state of BTO was confirmed by differential scanning calorimetry and ultrasonic spectroscopy. The addition of BTO into PDMS strongly affects the dielectric properties of the composites. At low temperatures close to 160 K, the PDMS matrix exhibits a dielectric anomaly related to a dynamic glass transition, which shifts to higher temperatures as the BTO content increases due to the strong interaction between polymer chains and nanoparticles. Ultrasonic measurements demonstrate the appearance of a piezoelectric voltage signal on a thin plate of the composite with the highest available filler concentration (23 vol %) under longitudinal stress applied by a 10 MHz ultrasonic wave. As a result, at room temperature, the detected signal is characterized by output voltage and specific stored energy values of 10 mV and 367.3 MeV/m2, respectively, followed by a further increase with cooling to 35 mV at 150 K. The proposed BTO/PDMS composite system is thus a potential candidate for nanogenerators, namely, a simple, flexible, and lead-free device converting high-frequency (10 MHz) mechanical vibrations into electrical voltage.

Enabling high dielectric constant and low loss tangent in BaTiO3–epoxy composites through a 3D interconnected network structure of ceramic phase

Constructing ceramic–polymer composites with a 3–3 connectivity is an effective strategy to achieve a notable increase in the dielectric constant at low ceramic contents. However, the dielectric data of the 3–3 composites with a low ceramic content (<10 vol. %) are still limited, and further investigation is thus required. Herein, composites with a 3–3 connectivity, in which BaTiO3 (BTO) and epoxy are self-connected in three dimensions, were developed and constructed at low BTO contents (2.0–8.3 vol. %). A three-dimensional network structure of the BTO ceramic (3D-BTO) was constructed via the sacrificial template method using polyurethane foam as the template. The dielectric constant and loss tangent of the composites increased with increasing BTO content. At a BTO content of 8.3 vol. %, the dielectric constant of the composite considerably increased to 33.4 at 1 kHz, which was ∼10-fold higher than that of neat epoxy (3.5). The loss tangent had a low value of< 0.030. By comparing with several theoretical models, the dielectric constants of the composites were well fitted with the effective medium theory model at low fitting factors (n = 0.008–0.013). The considerable increase in the dielectric constant of the composites with a low loss tangent at a low BTO content was attributed to the strong interfacial polarization and continuous polarization pathways through the interconnected 3D-BTO network structure in the composites. This study fills the gap in the literature by providing missing data on the dielectric properties of 3–3 composites at low ceramic contents (<10 vol. %), as well as a theoretical prediction.