Search

To improve densification of the (Ba0.85Ca0.15)(Hf0.1Ti0.9)O3 (BCHT) ceramics prepared via powder injection moulding, MnO2 and Li2CO3 were used as sintering aids. The BCHT ceramics doped with different Mn- and Li-amount prepared by powder injection moulding in which paraffin was used as injection binder, have rather pure perovskite structure with complicated polymorphic ferroelectric phase coexistence. Polyhedral grains combined with nearly round shape grains with increased relative density and larger gains size were obtained at appropriate doping amount, related to the formation of liquid phase during sintering and increased mobility of ions due to the generation of point defects caused by heterovalent cations doping. TheMn- and Li-doped BCHT ceramics are displacement driven ferroelectrics with apparent diffused transition characteristic at different extent, relating to the morphotropic phase boundary composition and the variation of point defects induced by doping. Comparable or surpassing electrical performance was acquired, especially the dielectric breakdown strength was increased due to the improved sinterability. With appropriate doping amount, piezoelectricity larger than 300 pC/N can be obtained in the Mn- and Li-doped BCHT ceramics poled under low electric field.

A novel glass additive of 10Bi2O3‒5Li2O‒7.5Na2O‒7.5K2O‒21Nb2O5‒20.5SiO2‒10.5BaO‒11SrO‒4.5Al2O3‒0.5La2O3‒2TiO2 was melted to improve the energy‐storage properties of (Ba0.94Li0.02La0.04)(Mg0.04Ti0.96)O3 (BLLMT) ceramics (BLLMT‒x wt% G), which overcomes the paradox between polarization and voltage endurance. The dielectric constant and resistance of BLLMT ceramics are improved by glass modification, while the grain size decreases. Consequently, excellent breakdown strength of 565.9 kV/cm is obtained, and the difference between maximum polarization and remnant polarization reaches up to 22.14 µC/cm2. Weibull distribution and finite element simulation prove that grain boundary density, grain size, resistance, and bandgap width have significant effects on the breakdown strength. Finally, outstanding energy‐storage density of 4.82 J/cm3 is obtained at x = 2, accompanied with an excellent pulse discharged energy density of 3.42 J/cm3, current density of 1226.12 A/cm2, and power density of 337.19 MW/cm3. Excellent temperature stability is gained with the variation of the pulse discharged energy density less than 10% at 20°C‒140°C. The outstanding pulse energy‐storage parameters are related to phase structure, small grain size, high grain boundary density, formation of liquid phase, increased ceramic resistance, and destroyed long‐range ordered ferroelectrics. This work provides a novel idea for fabricating glass to obtain excellent energy‐storage performance and promotes practical application of BaTiO3 ceramics. [ABSTRACT FROM AUTHOR]

The unprecedented navigation ability in micro/nanoscale and tailored functionality tunes micro/nanomotors as new target drug delivery systems, open up new horizons for biomedical applications. Herein, we designed a light-driven rGO/Cu2 + 1O tubular nanomotor for active targeting of cancer cells as a drug delivery system. The propulsion performance is greatly enhanced in real cell media (5% glucose cells isotonic solution), attributing to the introduction of oxygen vacancy and reduced graphene oxide (rGO) layer for separating photo-induced electron-hole pairs. The motion speed and direction can be readily modulated. Meanwhile, doxorubicin (DOX) can be loaded quickly on the rGO layer because of π-π bonding effect. The Cu2 + 1O matrix in the tiny robots not only serves as a photocatalyst to generate a chemical concentration gradient as the driving force but also acts as a nanomedicine to kill cancer cells as well. The strong propulsion of light-driven rGO/Cu2 + 1O nanomotors coupled with tiny size endow them with active transmembrane transport, assisting DOX and Cu2 + 1O breaking through the barrier of the cell membrane. Compared with non-powered nanocarrier and free DOX, light-propelled rGO/Cu2 + 1O nanomotors exhibit greater transmembrane transport efficiency and significant therapeutic efficacy. This proof-of-concept nanomotor design presents an innovative approach against tumor, enlarging the list of biomedical applications of light-driven micro/nanomotors to the superficial tissue treatment. [ABSTRACT FROM AUTHOR]

Chunks are multi-word sequences that constitute an important component of the mental lexicon. In second language (L2) acquisition, chunking is essential for attaining fluency and idiomaticity. In the present study, in order to examine whether chunks provide a processing advantage over non-chunks for L2 learners at different levels of proficiency, three groups (beginner, intermediate, and advanced) English-speaking learners of Chinese participated in an online acceptability judgment task and a familiarity rating task. Our results revealed that the participants in all three groups processed chunks faster and with fewer errors than they did non-chunks. It was also found that the observed processing advantage of chunks could not be explained by a familiarity effect alone, thus suggesting that L2 learners across the board store chunks as holistic units. The implications of chunk instruction in relation to input frequency and variability in L2 settings are also discussed. [ABSTRACT FROM AUTHOR]

Via composition designing and sintering condition tailoring, high-density pure perovskite structure xBi(Ni0.50Ti0.50)O3–0.05BiFeO3–(0.95−x)Pb(Zr0.50Ti0.50)O3 [xBNT–0.05BF–(0.95−x)PZT, x = 0.19, 0.20, 0.21, 0.22, 0.23] ceramics were prepared by solid-state sintering method with adding additional 0.5 wt% LiBO2 sintering aid, whose sintering temperature was lower than that reported in literature. The xBNT–0.05BF–(0.95−x)PZT ceramics have mainly tetragonal structure confirmed by X-ray diffraction measurement and Raman spectroscopy, which is affected by composition and sintering condition. Broad dielectric peaks appear in all samples, and diffusive phase transition and dielectric frequency dispersion are obvious as well. The 0.20BNT–0.05BF–0.75PZT ceramics exhibit large piezoelectricity d33 = 386 pC/N combined with rather high dielectric constant maximum temperature Tm = 264°C, presenting enormous application potential in the high-temperature piezoelectric-related field. [ABSTRACT FROM AUTHOR]

Polyvinylidene fluoride (PVDF)/[(Ba0.85Ca0.15)0.995Sm0.005](Ti0.9Hf0.1)O3 (BCTH-0.005Sm3+) composite films with different BCTH-0.005Sm3+ filling amount were prepared via hydrothermal method and solution tape scraping process. The effects of BCTH:0.005Sm3+ filling amount were characterized by X-ray diffractometer (XRD), Fourier transform infrared spectrum (FTIR), ultraviolet-visible (UV-vis) transmission spectrum and photoluminescence spectrum. XRD confirms appropriate amount filling of BCTH:0.005Sm3+ promoting formation of β-phase, and FTIR reveals coupling between PVDF matrix and BCTH:0.005Sm3+ filler in the composite films. BCTH:0.005Sm3+ nanopowder filling increases optical transmittance, widens visible light region, and induces redshift of maximum absorption of pure PVDF. Emission intensity and fluorescence lifetime increase first and then decrease with increasing BCTH:0.005Sm3+ filling amount, and one-photon assisted down-conversion process dominates fluorescence emission in the PVDF/BCTH:0.005Sm3+ composite films. Overall, filling 2 wt% BCTH:0.005Sm3+ nanopowder is more helpful to improve comprehensive performance of the composite films, broadening prospect application in electrical and optical multifunctional fields. [ABSTRACT FROM AUTHOR]

Rolling contact fatigue (RCF) cracks online detection using eddy current testing (ECT) is in urgent demand. However, RCF cracks detection and evaluation in this way under moving conditions remains challenging due to the velocity effect in ECT. This paper aims to study the response of a transmitter-receiver eddy current probe to cracks under moving conditions and evaluate the depth and inclination angle of RCF cracks. In this paper, a high-speed eddy current testing system is developed to experimentally investigate the influence of coil gap, detection speed, and the lift-off on the eddy current probe's response under moving conditions. In addition, the temporal and amplitude features of the eddy current signal are extracted to characterise the depth and inclination angle of the RCF cracks. The experimental results indicate the eddy current probe's response can be improved by increasing the coil gap (coil centre distance) suitably, which can be done to compensate for the attenuation of the eddy current signal caused by detection speed and lift-off. The probe's response hardly changes with an increase in detection speed when the driver and pick-up coils of the eddy current probe completely overlap. The crack depth and inclination angle can be evaluated under moving conditions. [ABSTRACT FROM AUTHOR]

(1-x)(Ba0.75Sr0.1Bi0.1)(Ti0.9Zr0.1)O3-x(Sb0.5Li0.5)TiO3 (abbreviated as BSBiTZ-xSLT, x = 0.025, 0.05, 0.075, 0.1) ceramics were prepared via a conventional solid-state sintering method under different sintering temperatures. All BSBiTZ-xSLT ceramics have predominantly perovskite phase structures with the coexistence of tetragonal, rhombohedral and orthogonal phases, and present mainly spherical-like shaped grains relating to a liquid-phase sintering mechanism due to adding SLT and Bi2O3. By adjusting the sintering temperature, all compositions obtain the highest relative density and present densified micro-morphology, and doping SLT tends to promote the growth of grain size and the grain size distribution becomes nonuniform gradually. Due to the addition of heterovalent ions and SLT, typical relaxor ferroelectric characteristic is realized, dielectric performance stability is broadened to ~120 °C with variation less than 10%, and very long and slim hysteresis loops are obtained, which is especially beneficial for energy storage application. All samples show extremely fast discharge performance where the discharge time t0.9 (time for 90% discharge energy density) is less than 160 ns and the largest discharge current occurs at around 30 ns. The 1155 °C sintered BSBiTZ-0.025SLT ceramics exhibit rather large energy storage density, very high energy storage efficiency and excellent pulse charge–discharge performance, providing the possibility to develop novel BT-based dielectric ceramics for pulse energy storage applications. [ABSTRACT FROM AUTHOR]