Effect of the element ratio in the doping component on the properties of 0.975(0.8Bi1/2Na1/2TiO3–0.2Bi1/2K1/2TiO3)–0.025Bix/3Mgy/3Nbz/3O3 ceramics

A new series of ternary perovskite 0.975(0.8Bi Na TiO –0.2Bi K TiO )–0.025Bi Mg Nb O (BNT–BKT–BMN, BMN‐xyz) ceramics were designed and synthesized. The effect of the element ratio in the doping component BMN on the strain, ferroelectric, piezoelectric, and dielectric properties of the BNT–BKT matrix were studied. The BMN‐430 composition without Nb element exhibits the typical features of non‐ergodic relaxor, which is characterized by a higher piezoelectric coefficient d and a butterfly‐shaped strain curve with negative strain. The introduction of trace Nb can significantly enhance the ergodicity of the system, reflecting in the high positive strain response and strain coefficient (d33∗>750pm/V) of BMN‐321 composition. In contrast, there is no significant difference in the properties between the presence and absence of Mg element. The temperature‐dependent electrical behaviors of BMN‐xyz ceramics were analyzed based on impedance spectroscopy. This study may be helpful to the design of the chemical modification strategy for the BNT‐based relaxor ferroelectrics. [Figure not available: see fulltext.] 1/2 1/2 3 1/2 1/2 3 x /3 y /3 z /3 3 3

Electro-mechano-optical properties of the Er³⁺ modified Bi_0.5Na_0.4K_0.1TiO₃ versatile ceramics

A series of Bi Er Na K TiO (BNKT-xEr) ceramics were designed and fabricated, the dopant effects on dielectric, piezoelectric and photoluminescence properties were studied. The results show that the piezoelectric property of BNKT can be enhanced by a trace amount of Er dopant, which is also reflected in the large linear electrostrain (S = 0.29%, under 55 kV/cm) achieved in BNKT-0.0025 Er. On the other hand, higher Er content can produce excellent dielectric temperature stability, with △ԑ/ԑ < ±15% over temperature range of 90∼510 °C. Meanwhile, all BNKT-xEr ceramics exhibit good photoluminescence properties, which may open new applications of these multifunctional ceramics. 0.5- x x 0.4 0.1 3 uni 150 °

Cyanuric Acid-Assisted Synthesis of Hierarchical Amorphous Carbon Nitride Assembled by Ultrathin Oxygen-Doped Nanosheets for Excellent Photocatalytic Hydrogen Generation

Amorphous carbon nitride with typical short-range order arrangement as an effective photocatalyst is worth exploring but remains a great challenge because its disordered structure induces severe recombination of photogenerated charge carriers. Herein, for the first time, we demonstrate that a hierarchical amorphous carbon nitride (HACN) with structural oxygen incorporation can be synthesized via a cyanuric acid-assisted melem hydrothermal process, accompanied by freeze-drying and pyrolysis. The complex composed of melem and cyanuric acid exhibiting a unique 3D self-supporting skeleton and significant phase transformation is responsible for the formation of an interconnected hierarchical framework and amorphous structure for HACN. These features are beneficial to enhance its visible light harvesting by the multiple-reflection effect within the architecture consisting of more exposed porous nanosheets and introducing a long band tail absorption. The well-designed morphology, band tail state, and oxygen doping effectively inhibit rapid band-to-band recombination of the photogenerated electrons and holes and facilitate subsequent separation. Accordingly, the HACN catalyst exhibits exceptional visible light (λ > 420 nm)-driven photoreduction for hydrogen production with a rate of 82.4 μmol h–1, which is 21.7 and 9.5 times higher than those of melem-derived carbon nitride and crystalline nanotube carbon nitride counterparts, respectively, and significantly surpasses those of most reported amorphous carbon nitrides. Our controlling of rearrangement of the in situ supramolecular self-assembly of melem oligomer using cyanuric acid directly instructs the development of highly efficient amorphous photocatalysts for converting solar energy into hydrogen fuel