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In this work, Bi 0.5 (Na 0.82 K 0.18 ) 0.5 Ti 1– x (Mg 1/3 Nb 2/3 ) x O 3 (BNKT– x MN) lead-free ceramics with x  = 0.02–0.045 were fabricated by conventional solid state reaction sintering method. The effects of MN content on the phase structure, microstructure, dielectric, ferroelectric, energy storage and strain response were investigated. The MN diffuses into the lattice of BNKT matrix and forms solid solution. The MN doping pinches the hysteresis loops, and improves the energy storage density and efficiency. Meanwhile, the electric field-induced strain response with low hysteresis is also promoted. The B-site modification induces the transition from ferroelectric phase to ergodic relaxor. The significant enhancement in energy storage and strain response is attributed to the compositionally induced phase transition. A noticeable diffuse phase transition is confirmed by dielectric analysis. Thus, the energy storage and strain properties of BNKT ceramics can be modified by complex-ion induced phase transition. [ABSTRACT FROM AUTHOR]

This work compared the effects of sintering methods on the structure, dielectric, strain and energy storage properties of (Bi0.5Na0.5)0.94Ba0.06Ti0.965(Mg1/3Nb2/3)0.035O3 (BNBT-0.035MN) lead-free ceramics. The single phase perovskite structure of BNBT-0.035MN ceramics was independent with sintering methods. The ceramics by two-step sintering had smaller grain size and denser microstructure than those of the ceramics by traditional sintering. Compared with traditional sintering, the ceramics by two-step sintering exhibited better energy storage properties. The optimum energy storage density (W = 0.80 J/cm3) and corresponding efficiency (η = 65%) were obtained at 70 kV/cm, while the electric field-induced strain decreased. Dielectric properties of two-step sintering samples were inferior to that of traditional samples, which is related to the grain size effect. [ABSTRACT FROM AUTHOR]

Lead-free [(BiNa)Ba]LaTiO (BNBLT) ceramics for energy storage application were prepared by traditional solid-state reaction technique, and the La ions doping content was varied at 0 ≤ x ≤ 0.04. The BNBLT ceramics showed single-phase perovskite structure without impurity phase. Compact and uniform microstructure with fine grain size was obtained. The remanent polarization and coercive field decreased with the increase in La ions doping content, and the energy storage density increased drastically. The maximum energy storage density of the BNBLT ceramics at x = 0.04 was 1.09 J/cm by using LaO powders and can be further increased to 1.21 J/cm using La(NO) powders, and meanwhile, the breakdown field strength increased obviously. Anti-ferroelectric-like behavior with a double pinched P- E hysteresis loop was observed in La-doped BNBLT ceramics at room temperature, which is promising candidate for energy storage dielectric ceramic. [ABSTRACT FROM AUTHOR]

The influence of B-site (Al 0.5 Nb 0.5 ) 4+ complex-ion substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy-storage properties of Bi 0.5 (Na 0.82 K 0.18 ) 0.5 Ti 1– x (Al 0.5 Nb 0.5 ) x O 3 (BNKT- x AN) ceramics were systematically investigated. BNKT- x AN ceramics showed single-phase perovskite structure without an obvious phase transition after adding AN. Compact and uniform microstructure with almost the same grain morphology and size was obtained. The AN doping produced slimmer P - E loops and thus improved energy storage property. Meanwhile, the energy storage density increases drastically, and a maximum value of 1.41 J/cm 3 at 105 kV/cm was achieved in BNKT-0.08AN through increasing greatly its breakdown strength with more AN content. The temperature dependence of dielectric constant and dielectric loss of BNKT- x AN ceramics illustrated the obvious relaxor phase transition characteristics. Low ionic conductivity and electronic conductivity indicated the BNKT- x AN ceramics have excellent dielectric properties. These results indicated that the BNKT-AN system may be a promising lead-free material for high energy storage density capacitor. [ABSTRACT FROM AUTHOR]

The influence of B-site (Al 0.5 Nb 0.5 ) 4+ complex-ion substitution on the phase transition, microstructure, dielectric, ferroelectric, and energy storage properties of (Bi 0.5 Na 0.5 ) 0.94 Ba 0.06 Ti 1− x (Al 0.5 Nb 0.5 ) x O 3 (BNBT -x AN) ceramics was systematically investigated. BNBT- x AN ceramics showed single-phase perovskite structure without an obvious phase transition after adding AN. Compact and uniform microstructure with almost the same grain morphology and size was obtained. The AN doping produced slimmer P – E loops and thus improved energy storage property. At the composition of x =0.04 and electric field of 70 kV/cm, the energy storage density achieved the optimum value of 0.70 J/cm 3 . The temperature dependence of dielectric constant ε r and dielectric loss tan δ illustrated a noticeable diffuse phase transition characteristics in BNBT -x AN ceramics. These results indicated that the BNBT-AN system may be a promising lead-free material for high energy storage density capacitor. [ABSTRACT FROM AUTHOR]