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[(Na1−xKx)0.5Bi0.5]Ti0.985Ta0.015O3 (abbreviated as Ta-NK100x) lead-free ceramics with good piezoelectric properties were prepared using a solid-state reaction method. The structure and electrical properties of Ta-NK100x had been systemically investigated. The highest bipolar strain of 0.458% and the unipolar strain 0.448% are achieved at x = 0.18 at 60 kV/cm. Meanwhile, the corresponding normalized strain d33∗ reaches 747 pm/V. In addition, the unipolar strain of the poled Ta-NK18 increases to 0.537%, and corresponding d33∗ increases slightly to 894.5 pm/V at 60 kV/cm. The electric-field-induced phase transition between ferroelectric and relaxor is found to play a dominant role in the origin of the large strain. Moreover, the strain behavior remains stable within 105 switching cycles which indicating the prepared ceramics are promising candidates for actuators and stress sensors. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C3N4), a new two-dimensional (2D) polymeric semiconductor, is considered as one of the most promising candidates for visible-light photocatalytic H2 evolution. The synthesis of thin-layered g-C3N4 is a facile approach to enhancing its photocatalytic properties. Here, a novel, cost-efficient, and time-saving strategy is reported to obtain 2D g-C3N4. In this equipment, bulk g-C3N4 and thin-layered g-C3N4 (denoted as G-CN) assembled from gaseous molecules were obtained simultaneously. The thin-layered g-C3N4 possesses more negative conduction-band minimum (~ 0.18 eV) relative to the bulk counterparty, leading to stronger redox ability. What is more, the carrier mobility and separation efficiency are both improved. As a result, the water splitting performance and photodegradation efficiency for methylene blue on thin-layered g-C3N4 are dramatically improved. The H2 evolution rate and half-time of photodegradation obtained by kinetic fitting reached 48.83 μmol h−1 and about 1.5 h, which is much more superior to that of bulk g-C3N4. Generally, the present work may bring out new thinking to synthesize thin-layered 2D materials. [ABSTRACT FROM AUTHOR]

Large energy-storage density is observed in BaZrO (BZ)-modified 0.80BiNaTiO-0.20BiKTiO (BNBK) lead-free ferroelectric (FE) ceramics synthesized by conventional solid-state reaction. The energy-storage property of (1 − x)BNBK- xBZ has been investigated. Certain content of BZ can enhance the energy-storage property of BNBK by enhancing the breakdown strength. The largest energy-storage density W = 0.73 J/cm and efficiency of energy storage η = 0.75 at E = 70 kV/cm are achieved in the 0.96BNBK-0.04BZ, which is significantly higher than that of BNT-based and lead-containing FE materials reported. Its energy-storage density exhibits the superior thermal stability with temperature range of 30-100 °C. Those properties promise that the environmental friendly (1 − x)BNBK- xBZ ceramics are candidate for applications of energy-storage devices. [ABSTRACT FROM AUTHOR]

Functionalized graphene/ZnO (FGZnO) nanohybrids with strong chemical coupling and electronic interaction were synthesized through a modified in situ synthesis method by combining two procedures: functionalization of graphene oxides and solution-based synthesis of FGZnO. ZnO species with morphologies of nanorods or nanoplates were densely attached on the graphene sheets. The effectiveness of this method for loading ZnO onto graphene with good interface contact was confirmed by using scanning electron microscopy, transmission electron microscopy, XPS measurements, and UV-Vis spectroscopy. Gas sensors based on the nanohybrids have faster response, higher sensitivity, and better selectivity to ethanol compared with pure ZnO nanorods. The mechanisms to interpret the formation of nanohybrids and their enhanced gas-sensing performance were put forward. [ABSTRACT FROM AUTHOR]

The perovskite oxides (1 − x)Bi0.5(Na0.9K0.1)0.5TiO3- xSrTi0.8Zr0.2O3 (SZT1000 x, x = 0, 0.2, 0.4, 0.6, 0.8, and 1 %) were prepared via the conventional solid-state reaction method. The room temperature ferroelectric P- E loops coordinate with polarization current density J- E curves illustrated the changes of ferroelectric domains and polar nanoregions under different driving fields exhaustively. The composition and electric field dependent strain behavior of this system were investigated to develop a lead-free piezoelectric material with a large strain response at a lower electric field. A large strain of 0.44 % (Smax/Emax = 744 pm/V) at an applied field of 50 kV/cm was obtained at the composition of 0.6 mol% SZT. Temperature-dependent hysteresis measurements reveal the primary origin of the large strain is due to the presence of a nonpolar phase at a zero field. Upon the application of an electric field, the nonpolar phase that can easily transform into a long-range ferroelectric phase, and then brings the system back to its unpoled state once the applied electric field is removed. Notably, the electric field required to deliver large strains is reduced to 40 kV/cm while the Smax/ Emax reached up to 717 pm/V, indicating that the developed material is highly promising for actuator applications. [ABSTRACT FROM AUTHOR]

The modified (Na 0.5Bi 0.5) 0.94Ba 0.03La 0.02Ti 0.995Mn 0.005O 3 lead-free ceramics were prepared using a traditional solid-state reaction process, and their structures were characterized by X-ray diffraction, scanning electron microscope, and Raman spectroscopy, respectively. A double-like P–E loop was discussed at the room temperature for the co-doped ceramics by reason of the appearance of the anti-ferroelectric. The ferroelectric hysteresis loop and field-induced strain were studied at different temperatures. A large strain ( S33 = 0.33 %, E = 50 kV/cm at 120 °C) was observed due to the transformation between ferroelectric and anti-ferroelectric phase at the phase transition temperature. Also, the depolarization temperature ( Td) of the co-doped ceramics was determined from the pyroelectric current density versus temperature plots, which was consistent with the result from the position of dielectric loss’s peak as a function of temperature. [ABSTRACT FROM AUTHOR]