Crystallization-temperature controlled alkali-free niobate glass-ceramics with high energy storage density and actual discharge energy density

Abstract

The niobate-based alkali-free ferroelectric glass-ceramics were realized through the synthesis of mother glass by way of melt-annealing technique, followed by temperature-controlled crystallization. As the crystallization temperature raised, the ratio of the ferroelectric crystal phase precipitated in the mother glass enhanced continuously, resulting in the enlargement of the permittivity. Attribute to the rise of grain size, pores and cracks tend to appear in the microstructure of glass-ceramics with high crystallization temperature, leading to lower breakdown strength. The theoretical simulation was applied to reveal the internal mechanism, exploring the outcome of heat treatment temperature on the breakdown electric field. The maximum theoretical energy storage density reaches to 18.44 J/cm3 at the crystallization temperature of 800 °C. The single-layer capacitor made from the G800 sample exhibited extremely high power density (230 MW/cm3) and superior actual discharge energy density (1.5 J/cm3) at 600 kV/cm. These results indicate that alkali-free niobate-based glass-ceramics is a kind of encouraging candidate material for pulse capacitors.