Effects of glass additions on the microstructure and dielectric properties of barium strontium titanate (BST) ceramics

摘要

Commercial glass frits (lead borosilicate glasses) were employed as the sintering aids to reduce the sintering temperatures of BST ceramics. The effects of the glass content and the sintering temperature on the microstructures, dielectric properties and tunabilities of BST ceramics have been investigated. Densification of BST ceramics of 5 wt percent glass content becomes significant from sintering temperature of 1000 deg C. The glass content shows a strong influence on the Curie temperature T_c, permittivity and the diffuse transition. X-ray results show all BST ceramics exhibit a perovskite structure and also the formation of a secondary phase, Ba_2TiSi2_O_8. The shift of BST diffraction peaks towards higher angle with increasing the glass content indicates the substitution of Pb~(2+) in Ba~(2+) site, which mainly accounts for the diffuse transition observed in these BST ceramics. BST ceramics with 10 wt percent glass additives possess the highest tunability at all four sintering temperatures. A tunability of 12.2 percent at a bias field of 1 kV/mm was achieved for BST ceramics with 10 wt percent glass content sintered at 900 deg C.