Effects of crystalline temperature on microstructures and dielectric properties in BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 glass-ceramics

The BaO-Na2O-Bi2O3-Nb2O5-Al2O3-SiO2 (BNBN-AS) glass-ceramics were prepared by technics of melt-quenching accompanied with process of controlled crystallization. According to the X-ray diffraction results, NaNbO3 with perovskite structure and Ba2NaNb5O15 with tungsten bronze structure were all precipitated at four different crystalline temperatures. With the increasing of crystalline temperature, the relative dielectric constant kept increasing, while breakdown strength (BDS) increased first and then decreased. The highest relative dielectric constant of 123 at 1000 ?C as well as optimal breakdown strength of 1878.75 +/- 63.2 kV/cm at 950 degrees C were acquired in this system. The theoretical energy-storage density was markedly enhanced up to the maximum value of 18.4 +/- 1.3 J/cm(3) at 950 degrees C, which is approximately twice than that at 850 degrees C. The discharged energy density reached to 0.48 J/cm(3) at the applied electric field of 600 kV/cm for the sample crystallized at 950 degrees C, which promises a broad application prospect.