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A series of novel Bi 0.38 Na 0.38 Sr 0.24 Ti (1- x) (Mn 1/3 Nb 2/3) x O 3 lead-free ceramics (BNST-100 x MN) were designed and fabricated. The dielectric, ferroelectric, energy-storage, electrostrain properties, and impedance performance of these materials were systematically investigated. A large strain response under low driving electric field was obtained that benefits from the enhanced relaxor-to-ferroelectric phase transition. The optimum piezoelectric stain coefficient d 33 * of 930 pm/V (under 40 kV/cm) was achieved in BNST-1MN composition. The substitution by MN dopant gave rise to a homogeneous micro-morphology with small grains that gave rise to an enhanced high breakdown strength (BDS). Slim and slanted ferroelectric hysteresis was obtained by introducing a larger amount of MN, and hence the BNST-2MN ceramic exhibits a high energy-storage density of 1.30 J/cm3 at 110 kV/cm, accompanied with an excellent fatigue-free behavior. The dielectric response exhibited a stable high temperature dielectric property with low dielectric loss. These results indicate that BNST-100 x MN ceramics are promising candidates for the actuator and energy storage applications. [ABSTRACT FROM AUTHOR]

A series of (1- x)(Bi 0.5 Na 0.5) 0.94 Ba 0.06 TiO 3 - x BaSnO 3 (BNBT-100 x BSN, x = 0–20) lead-free ceramics were synthesized using a conventional high-temperature solid-state reaction route. The effects of BaSnO 3 on the dielectric, ferroelectric and energy-storage performance of BNBT-BSN were systematically investigated. Temperature dependent permittivity curves indicated the obviously enhanced relaxor ferroelectric property. The introduction of BaSnO 3 reduced the temperature corresponding to the first dielectric anomaly, which facilitated the dielectric temperature stability. △ε'/ε' 150°C varied no more than 15% within the temperature range of up to 338 °C (45–383 °C) for BNBT-15BSN. A slimed P-E loop was obtained with the remnant polarization of 0.4 μC/cm2 for BNBT-15BSN. Moreover, the breakdown field intensity of BNBT-BSN increased effectively from 80 kV/cm to 115 kV/cm. Therefore, an optimum energy-storage performance was obtained in BNBT-15BSN with the energy-storage density of 1.2 J/cm3 whose energy-storage efficiency reached 86.7%. Furthermore, the possible contributions of defect and vacancy to relaxation and conductance mechanism were discussed by studying the impedance and electric modulus. The results above indicated the BNBT-100 x BSN be a promising lead-free candidate for energy-storage capacitors. [ABSTRACT FROM AUTHOR]

The development of high-performance catalysts for applications in advanced oxidation processes to degrade organic pollutants can contribute significantly to environmental protection. However, current nanoparticle-based catalysts are energy consuming, hazardous, and unrecyclable, therefore the development of clean energy-driven and reusable catalysts with high performance remains challenging. Herein, flexible barium titanate (BTO) nanofibers were fabricated via a combination of electrospinning and sol-gel methods. The large surface area, interconnected porous structure, good piezoresponse, and relatively high piezoelectric coefficient endow the resultant BTO nanofibers membranes with good piezocatalytic degradation performance toward organic contaminants. With the assistance of ultrasonic waves, the membranes could degrade 96% of organic dyes within 60 min, with a reaction rate of 0.0537 min−1. The radical detection and trapping experiments proved that superoxide radicals and holes played vital roles in piezocatalytic reaction process. Furthermore, the flexible BTO nanofibrous membranes with a tensile strength of 2.2 MPa exhibited good reusability over five cycles, without the tedious recycling operations needed for micro/nanoparticle-based catalysts. The successful fabrication of BTO nanofibrous membranes would provide a route for the fabrication of clean energy-driven and high-performance catalysts for wastewater treatment. [ABSTRACT FROM AUTHOR]

(1- x)[0.94(Bi 0.5 Na 0.5)TiO 3 -0.06BaTiO 3 ]- x Ba(Sn 0.70 Nb 0.24)O 3 (abbreviated as BNTBT-100 x BSN) lead-free ceramics were fabricated with a relative density greater than 96 %, and the structure as well as performance were tested. BNTBT-100 x BSN ceramics are pseudo-cubic perovskite structure, with dense surface morphology. Doping BSN can effectively reduce the dielectric loss of ceramics and increase the relaxation properties to a certain extent. The randomly distributed ferroelectric phase was replaced by polar nano regions, thereby improving the electro-strain and energy storage performance of the system. The largest electro-strain and the corresponding normalized strain (d 33 *) reach ~ 0.43 % and 633 pm/V respectively in the BNTBT-1BSN ceramic. The largest effective energy storage density reaching ~ 1.28 J/cm3 was tested in BNTBT-2BSN. BNTBT-100 x BSN ceramics provide a feasible idea for the systematic research of lead-free ferroelectrics and improvements in electro-strain and energy storage applications. [ABSTRACT FROM AUTHOR]

A series of lead-free (Bi 0.5 Na 0.5) 0.94 Ba 0.06 Ti 1- x (Y 0.5 Nb 0.5) x O 3 (for 0 ≤ x ≤ 0.03) perovskite ceramics were fabricated using a solid-state reaction technique. The effects of (Y 0.5 Nb 0.5)4+ ions doping on phase structure, piezoelectric properties, AC impedance, and fatigue resistance were systematically studied. Crystal structure as a function of the composition revealed a single perovskite lattice structure with dense micromorphology. The transition temperature of the non-ergodic and ergodic relaxor ferroelectric phase shifted to near ambient temperature with increasing composition, which was related to the destruction of the long-range ordered ferroelectric domains. Hence, the transformation of ferroelectric-to-relaxor phase was easier under applied electric field at room temperature. The ceramic for x = 0.01 composition attained a large unipolar strain of ~ 0.452% with a corresponding normalized strain (d 33 *) of ~ 603 pm/V under applied 75 kV/cm field. Besides, the excellent fatigue resistance of the sample was obtained after 105 switching cycles under 70 kV/cm. These phenomena demonstrated that (Bi 0.5 Na 0.5) 0.94 Ba 0.06 Ti 1- x (Y 0.5 Nb 0.5) x O 3 ceramics might be suitable for a wide range of electronic equipment applications such as actuators and sensors. [ABSTRACT FROM AUTHOR]