High-Q BZT Ceramics for Microwave Applications

摘要

Ba(Zn_(1/3)Ta_(2/3))O_3 (BZT) ceramics were prepared by solid-state reaction and sintered in air at temperatures in the range 1550-1650°C, for 2 hours. In order to improve the microwave and millimeter wave properties, annealing treatment at 1400°C for 10 hours was applied. The long-range order with a 2:1 ratio of Ta and Zn ions on the octahedral positions of the perovskite structure and the vibrational modes were investigated by using XRD and Raman spectroscopy as function of sintering temperature. Presence of small amount of secondary phase, Ba_8ZnTa_6O_(24), affects Q factor even in the dense, highly ordered samples. The dielectric parameters were measured in the microwave range by Hakki-Coleman method and were correlated with structural and optical properties. Sintering temperature higher than 1600°C are required for BZT ceramics in order to obtain low microwave loss (Q x f ～ 100 THz).