The (1 − x ) Bi (Fe 0.9 Al 0.05 Yb 0.05 ) O 3 – x BaTiO 3 (BFAYO- x BTO) ceramics were synthesized by microwave sintering (MWS) and conventional sintering (CS) methods. The crystal structure, surface morphology, dielectric and ferroelectric properties were investigated. XRD patterns show that BTO tetragonal and BFO rhombohedral phases coexist in both MWS and CS samples, and that the diffraction peaks of MWS samples shift to lower angles due to the larger ionic radius of Ba 2+ compared with Bi 3+ . The lattice constant of BFAYO- x BTO ceramics increases with the increase of BTO content. It was found that the average grain size of the MWS ceramic is much smaller than that of the CS ceramic. Dielectric measurements reveal that the dielectric loss and dielectric constant increase with BTO content increasing. The introduction of BTO into BFAYO-based ceramic contribute to the enhancement of the dielectric relaxation behavior. The P – E hysteresis loops demonstrate that the remnant polarization ( P r ) and the coercive field ( E C ) of the MWS samples are smaller than those of the CS samples. P r and E C first increase, then decrease and then increase again with the increase of BTO content. The maximum and minimum values of the remnant polarization were obtained at x = 0.25 and 0.3, respectively.
Yan Zhong,Jiaqi Wang,Longgang Wu,Kunshan Liu,Shengping Dai,Jing Hua,Guanggui Cheng,Jianning Ding
A microstructured surface has been applied in self-powered triboelectric pressure sensors to increase the charge-carrying sites and enhance the output performance. However, the microstructure increases the distance between the electrode and the triboelectric layer, and its influence on the output performance is unknown. Herein, we proposed a dome-conformal electrode strategy for a self-powered triboelectric nanogenerator (TENG) pressure sensor. With a simple reverse-dome adsorption process, an ultrathin triboelectric layer and Ag electrode can be made conformal to the dome PDMS structure. The TENG sensor is constructed with paper as a positive triboelectric layer. Compared with the device based on nonconformal structure, the conformal design strategy endows the device with a faster charge transfer and enhanced output voltage. By doping with BaTiO3, the outermost triboelectric layer can be easily modified to improve its ability of sustaining charge, and an ultrathin PDMS layer is coated on the triboelectric layer to expand the triboelectric polarity difference between two triboelectric layers so as to enhance the output voltage. The synergistic effects enable the optimized TENG sensor with a sensitivity of 0.75 V/kPa in the low-pressure region (0–26 kPa) and 0.19 V/kPa in the high-pressure range (26–120 kPa). Its application in human motion detection, grabbing water beakers, and noncontact distance testing has been demonstrated. This work provides a route such as a conformal structure design strategy to enhance the output performance of a microstructure-based TENG sensor.
Lead-free ferroelectric ceramics show promising applications in environmentally friendly optoelectronic devices, yet conventional Bi 0.5 Na 0.5 TiO 3 -based materials face challenges in achieving balanced enhancement of energy storage density and photoluminescence properties. In this study, the influence mechanism of the structural evolution of Bi 0.5 Na 0.5 TiO 3 -based ceramics on their energy storage and photoluminescence properties was systematically studied. It was found that the doping of BaTiO 3 and SrTiO 3 caused local structural distortion and oxygen octahedral tilt, and the introduction of larger radius ions in A-site significantly refined grain size and improved breakdown electric field, endowing 0.75Bi (703/1500) Dy (47/1500) Na 0.5 TiO 3 -0.25BaTiO 3 with a high recoverable energy density of 3.73 J/cm 3 and an outstanding efficiency of 85.62 % under 350 kV/cm, while 0.75Bi (703/1500) Dy (47/1500) Na 0.5 TiO 3 -0.25SrTiO 3 exhibited strong photoluminescence properties, suggesting its potential as a yellow-green phosphor for warm white LEDs. Besides, SrTiO 3 doping enhanced crystal field symmetry to suppress thermal quenching via reduced phonon coupling, simultaneously improving Dy 3+ 6 H 15/2 → 4 I 13/2 transitions through optimized parity-forbidden relaxation. These findings elucidate the pivotal role of structural engineering strategies in tailoring the energy storage and photoluminescence properties of Bi 0.5 Na 0.5 TiO 3 ceramics, thereby will be beneficial for advancing the development of high-performance multifunctional dielectric capacitors.
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