Piezoelectric properties of PZT by an ethylene glycol-based chemical solution synthesis

We have investigated a water-stable sol–gel method based on ethylene glycol as a solvent and bridging ligand for the synthesis of ferroelectric lead zirconate titanate in bulk and thin film forms. This method offers lower toxicity of the solvent, higher stability toward atmospheric moisture and a simplified synthetic procedure compared to traditional sol–gel methods. However, the piezoelectric properties of products produced using this method have yet to be systematically studied. We have measured the ferroelectric and piezoelectric properties and compared them to existing literature using different synthesis techniques. Ceramic pellets of Nb-doped lead zirconate titanate (PNZT) in the tetragonal phase were produced with high density and good piezoelectric properties, comparable to those reported in the literature and those found in commercial piezoelectric elements. In addition, a nine-layer thin film stack was fabricated by spin coating onto platinized silicon substrates. The films were crack-free and showed a perovskite grain structure with a weak (111) orientation. Piezoelectric measurements of the film showed a piezoelectric coefficient comparable to literature values and good stability toward fatigue

Fabrication of poly (vinylidene fluoride) films by ultrasonic spray coating; uniformity and piezoelectric properties

Piezoelectric Poly (vinylidene fluoride) (PVDF) films with high flexibility are a suitable and promising replacement for rigid ceramic piezoelectric materials. However, for this purpose, enhancing piezoelectric properties and adopting an industrial fabrication method are of great importance. In this study, 5–9 µm thick PVDF films were fabricated by a nozzle-less ultrasonic spray coating (USC) system, followed by an annealing process at 100 °C. By applying proper spraying parameters, we could obtain highly uniform films with large d33 values (48 pm/V) and 56% crystallinity. Results show that the uniformity of the films plays an important role in the final piezoelectric properties. Thus, ultrasonic spray coating method can be used for fabrication of large-scale piezoelectric films with no need for poling or stretching processes

From synthesis to application: High-quality flexible piezoelectric sensors fabricated from tetragonal BaTiO3/ P(VDF-TrFE) composites:High-quality flexible piezoelectric sensors fabricated from tetragonal BaTiO₃/ P(VDF-TrFE) composites

In this work, a simple process for fabrication of piezoelectric BaTiO3 /P(VDFTrFE) composites from synthesis to its application as a wearable piezoelectric sensor is presented. Addition of 10 wt% synthesized tetragonal BaTiO3 particles (200 nm in diameter) enhanced the mechanical and piezoelectric properties of P(VDF-TrFE) better than commercial cubic phase particles (&lt;100 nm in diameter). Although P(VDF-TrFE) and tetragonal BaTiO3 have opposite piezoelectric coefficients, BaTiO3 improved the performance of the final piezoelectric sensor by modifying the distribution of stress in the P(VDF-TrFE) matrix, reducing the viscosity, and causing the mechanical reinforcement of the composite films. This requires the uniform distribution of particles in the polymer matrix, which was succeeded by prior surface modification of the particles. Inverse piezoelectric properties of BaTiO3 /P(VDF-TrFE) composites were enhanced by obtaining a higher polarization (Pr = 6.18 µC/cm2) and dielectric constant value (εr = 30.3) compared to pure P(VDF-TrFE)(Pr = 4.23 µC/cm2, εr = 8.8). Furthermore, the ferroelectric and switching behavior in the composites happened at lower electric fields. With respect to direct piezoelectric properties, the voltage coefficient of this composite is 30% higher than the pure P(VDF-TrFE). By fabricating simple wearable piezoelectric sensors for finger joint movement detection, the composite device showed an enhancement in output voltage (2.1 times), power (4.6 times), and sensitivity (1.6 times) in comparison to the pure P(VDF-TrFE) sensor. The composite sensor with a sensitivity of 10.16 mV/N, is able to produce a maximum peak-to-peak output voltage of 400 mV by bending the finger without the need for any amplification or post-processing.</p

Ferroelectric, Dielectric and Electromechanical Performance of Ba0.92Ca0.08Ti0.95Zr0.05O3 Ceramics with an Enhanced Curie Temperature

Ba0.92Ca0.08Ti0.95Zr0.05O3 (BCZT8-5) ceramic materials have been scarcely studied as lead-free piezo/ferroelectrics despite their enhanced Curie temperature (&gt;100 °C) with respect to most studied BCZT compositions. In this work, homogeneous dense BCZT8-5 ceramics with grain size in the range of 20 μm, and optimum ferroelectric, dielectric, and electromechanical performance, were prepared by the mixed oxides route using moderate synthesis (1250 °C-2 h) and sintering (1400 °C-2 h) conditions. Thickness-poled thin disks and monomodal shear plate resonators were used for the determination of piezoelectric coefficients, coupling factors, elastic, and dielectric permittivity coefficients, including all losses, by iterative analysis of impedance curves at resonance. Furthermore, the thermal evolution of the piezoelectric characteristics at resonance was determined to assess the enhanced working range of the ceramics (≈100 °C). Ferroelectric hysteresis loops and strains vs. electric-field butterfly loops were also measured and showed soft behavior with Ec = 2 kV/cm, Pr = 12 μC/cm2 after a maximum applied field of 3 kV was used. The ceramics showed a high endurance of P-E cycles to electrical fatigue up to 107 cycles. Moreover, dielectric properties as a function of temperature were also accomplished and showed nearly normal ferroelectric behavior, characteristic of samples with low crystallographic disorder. Overall, these ceramics showed high sensitivity and higher stability than other currently studied BCZT compositions.<br/