Enhanced Piezo-Photocatalytic Performance of Na₀.₅Bi₄.₅Ti₄O₁₅ by High-Voltage Poling

The internal electric field within a piezoelectric material can effectively inhibit the recombination of photogenerated electron–hole pairs, thus serving as a means to enhance photocatalytic efficiency. Herein, we synthesized a Na₀.₅Bi₄.₅Ti₄O₁₅ (NBT) catalyst by the hydrothermal method and optimized its catalytic performance by simple high-voltage poling. When applying light and mechanical stirring on a 2 kV mm⁻¹ poled NBT sample, almost 100% of Rhodamine B solution could be degraded in 120 min, and the reaction rate constant reached as high as 28.36 × 10⁻³ min⁻¹, which was 4.2 times higher than that of the unpoled NBT sample. The enhanced piezo-photocatalytic activity is attributed to the poling-enhanced internal electric field, which facilitates the efficient separation and transfer of photogenerated carriers. Our work provides a new option and idea for the development of piezo-photocatalysts for environmental remediation and pollutant treatment

Quenching‐circumvented ergodicity in relaxor Na₁/₂Bi₁/₂TiO₃‐BaTiO₃‐K₀.₅Na₀.₅NbO₃

Quenching alkaline bismuth titanates from sintering temperatures results in increased lattice distortion and consequently higher depolarization temperature. This work investigates the influence of quenching on the ergodicity of relaxor Na₁/₂Bi₁/₂TiO₃‐BaTiO₃‐K₀.₅Na₀.₅NbO₃. A distinct departure from ergodicity is evidenced from the increase in remanent polarization and the absence of frequency dispersion in the permittivity response of poled samples. Further, the samples exhibit enhanced negative strain upon application of electric field, indicating proclivity towards correlated polar nanoregions, corroborated by the enhanced tetragonal distortion. As a result, ergodic relaxor Na₁/₂Bi₁/₂TiO₃‐6BaTiO₃‐3K₀.₅Na₀.₅NbO₃ exhibits a depolarization temperature of 85°C with a 60% increase in remanent polarization and approximately a threefold increase in remanent strain upon quenching. Quenching‐induced changes in the local environment of Na⁺ and Bi³⁺ cations hinder the development of ergodicity promoted by the A‐site disorder. These results provide new insight into tailoring ergodicity of relaxor ferroelectrics

Soft and Hard Piezoelectric Ceramics for Vibration Energy Harvesting

The question as to which piezoelectric composition is favorable for energy harvesting has been addressed in the past few years. However, discussion on this topic continues. In this work, an answer is provided through a feasible method which can be used in selecting piezoelectric material. The energy harvesting behavior of hard (P4 and P8) and soft (P5 and P5H) lead zirconate titanate (PZT) ceramics was investigated. The results show that the maximum piezoelectric voltage coefficient g33 and transduction coefficient d33 × g33 were obtained in P5 ceramic. Meanwhile, the power generation characteristics at low frequencies were compared by the vibration energy harvester with a cantilever beam structure. The results indicate that the energy harvester fabricated by the P5 ceramic with the maximum d33 × g33 values also demonstrated the best power generation characteristics. The results unambiguously demonstrate that the power density and energy conversion efficiency of the energy harvesting devices are dominated by the d33 × g33 value of the piezoelectric materials

Enhanced Piezo-Photocatalytic Performance of Na₀.₅Bi₄.₅Ti4O₁₅ by High-Voltage Poling

The internal electric field within a piezoelectric material can effectively inhibit the recombination of photogenerated electron–hole pairs, thus serving as a means to enhance photocatalytic efficiency. Herein, we synthesized a Na0.5Bi4.5Ti4O15 (NBT) catalyst by the hydrothermal method and optimized its catalytic performance by simple high-voltage poling. When applying light and mechanical stirring on a 2 kV mm−1 poled NBT sample, almost 100% of Rhodamine B solution could be degraded in 120 min, and the reaction rate constant reached as high as 28.36 × 10−3 min−1, which was 4.2 times higher than that of the unpoled NBT sample. The enhanced piezo-photocatalytic activity is attributed to the poling-enhanced internal electric field, which facilitates the efficient separation and transfer of photogenerated carriers. Our work provides a new option and idea for the development of piezo-photocatalysts for environmental remediation and pollutant treatmen

A composite approach boosts transduction coefficients of piezoceramics for energy harvesting

Piezoelectric energy harvesting is a hotspot in the field of new energy, the core goal of which is to prepare piezoceramics with a high transduction coefficient (d33×g33). The traditional solid–solution design strategy usually causes the same variation trend of d33 and εr, resulting in a low d33×g33 value. In this work, a composite design strategy was proposed that uses PZN–PZT/ZnAl2O4 as an example. By introducing ZnAl2O4, which is nonferroelectric with low εr, to the PZN–PZT piezoelectric matrix, εr decreased rapidly while d33 remained relatively stable. This behavior was ascribed to the increase of Q33 caused by an interfacial effect facilitating the formation of micro-domain structure

Significantly Enhanced Poling Efficiency of Piezocomposites by Tuning Resistivity of a Polymer Matrix

Although the ability to convert biomechanical vibrations into electric energy has been demonstrated in organic–inorganic piezocomposites, it is challenging to improve their piezoelectric properties owing to insufficient electric field poling. Here, we propose a facile and effective approach to enhance the poling efficiency of a barium calcium zirconate titanate/polydimethylsiloxane (BCZT/PDMS) composite by introducing copper nanowires (Cu NWs) to tune the resistivity of the PDMS matrix. The Cu NW-modified PDMS weakens the resistivity mismatch between the BCZT filler and the PDMS matrix, allowing a higher poling electric field to be applied to the BCZT filler during poling. As a result, the BCZT/Cu-PDMS piezocomposite exhibited a high piezoelectric quality factor (d33 × g33) of 2.58 pm2/N, which was about 7 times higher than that of BCZT/PDMS (d33 × g33 = 0.38 pm2/N). Moreover, BCZT/Cu-PDMS showed a much higher power density (3.18 μW/cm2) and a faster charging capability. This composite approach of introducing metal nanowires can be considered as a generic poling-improvement method that can be extended to other organic–inorganic piezocomposite systems