Relaxor behavior of BaTiO3-BiYO3 perovskite materials for high energy density capacitors

Dielectric materials with high dielectric constant and breakdown voltage are very promising for pulsed energy storage applications. In this paper, (1-x) BaTiO3-xBiYO(3) (x=0-0.5) ceramics were synthesized using conventional solid-state reaction method. The ceramic structure transformed from ferroelectric tetragonal phases (x <=.0.5) to pseudo-cubic phases (x >= 0.1). When x=0.2, beyond the solid solubility limit of BaTiO3-BiYO3, the second phase and glassy phases were formed, accompanying lattice parameter excursion. It revealed a gradual change from classic ferroelectric behavior in pure BaTiO3 to highly diffusive and dispersive relaxor-like characteristics with BiYO3 content increasing. It exhibited high polarization maximum and low remnant polarization, which was favorable for energy storage in (1-x)BaTiO3-xBiYO(3) ceramics, due to the disrupted long polarization, the created weak coupling and the formed second phase. Furthermore, the nonlinearity of the (1-x) BaTiO3-xBiYO(3) ceramics were weakened obviously. A maximum energy storage density of 0.316 J/cm(3) at 66 kV/cm with relative high energy efficiency of 82.7% was achieved in 0.8BaTiO(3)-0.2BiYO(3) ceramic, which indicated that (1-x)BaTiO3-xBiYO(3) ceramics were promising lead-free relaxor materials for energy storage applications.