Formation mechanism, dielectric properties, and energy-storage density in LiNbO3-doped Na_(0.47)Bi_(0.47)Ba_(0.06)TiO_3 ceramics

摘要

The development of ferroelectric (FE) ceramics with high recoverable energy-storage density (W_(rec)) critically affects the miniaturization and integration of advanced pulse-power capacitors. However, most lead-free FE materials have the shortcomings of large remanent polarization and low dielectric breakdown strength. In this work, a strategy of composition control was implemented to improve the W_(rec) of lead-free ceramics. The effects of Li and Nb ion incorporation on the structure, dielectric, and ferroelectric properties of the highly insulating (Na_(0.5)Bi_(0.5))TiO_3-BaTiO_3 (NBT-BT) ceramic was investigated. X-ray diffraction analysis of the samples revealed that the pure phase was isostructural to (Na_(0.5)Bi_(0.5))TiO_3. Dielectric measurements exhibited two pronounced anomalies which shift a certain angle within the depolarization-temperature range. The effects of LiNbO_3 content on the breakdown characteristics and discharge energy storage of NBT-BT ceramics were investigated. An enhanced discharged energy density of 1.05 J/cm~3, calculated from a hysteresis loop, was observed at x = 4 mol%. The improved structure also resulted in an increase of up to 61 % in breakdown strength.