24 research outputs found
Enhanced Piezo-Photocatalytic Performance of Naā.ā Biā.ā TiāOāā by High-Voltage Poling
The internal electric field within a piezoelectric material can effectively inhibit the recombination of photogenerated electronāhole pairs, thus serving as a means to enhance photocatalytic efficiency. Herein, we synthesized a Naā.ā
Biā.ā
TiāOāā
(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 mmā»Ā¹ 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 Ć 10ā»Ā³ minā»Ā¹, 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
Quenchingācircumvented ergodicity in relaxor Naā/āBiā/āTiOāāBaTiOāāKā.ā Naā.ā NbOā
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 Naā/āBiā/āTiOāāBaTiOāāKā.ā
Naā.ā
NbOā. 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 Naā/āBiā/āTiOāā6BaTiOāā3Kā.ā
Naā.ā
NbOā exhibits a depolarization temperature of 85Ā°C with a 60% increase in remanent polarization and approximately a threefold increase in remanent strain upon quenching. Quenchingāinduced changes in the local environment of Naāŗ and BiĀ³āŗ cations hinder the development of ergodicity promoted by the Aāsite 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 Naā.ā Biā.ā Ti4Oāā by High-Voltage Poling
The internal electric field within a piezoelectric material can effectively inhibit the recombination of photogenerated electronāhole 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 mmā1 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 Ć 10ā3 minā1, 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 (d33Ćg33). The traditional solidāsolution design strategy usually causes the same variation trend of d33 and Īµr, resulting in a low d33Ćg33 value. In this work, a composite design strategy was proposed that uses PZNāPZT/ZnAl2O4 as an example. By introducing ZnAl2O4, which is nonferroelectric with low Īµr, to the PZNāPZT piezoelectric matrix, Īµr 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 organicāinorganic 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 Ć g33) of 2.58 pm2/N, which was about 7 times higher
than that of BCZT/PDMS (d33 Ć g33 = 0.38 pm2/N). Moreover, BCZT/Cu-PDMS
showed a much higher power density (3.18 Ī¼W/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 organicāinorganic piezocomposite
systems