Search

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]

(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]