Structure and microwave dielectric properties of Ba1+x(Co0.7Zn0.3)1/3Nb2/3]O3 (-0.015 ≤ x ≤ 0.015)

The sintering behavior, ordering state and microwave dielectric properties of Ba1+x(Zn0.3Co0.7)(1/3)Nb-2/3 Ceramics (-0.015 <= x <= 0.015) were investigated in this paper. The X-ray diffraction (XRD) results show that all samples exhibit a single phase except for the sample with x = -0.015. Scanning electron microscopy (SEM) observation and energy dispersion analysis (EDS) indicate that the second phase is barium niobate. Raman spectrum reveal the presence of long range order (LRO) of B-site ions when -0.015 <= x <= 0 and only short range order (SRO) when 0 <= x <= 0.015. The sinterability is decreased for the samples with x > 0. The dielectric constant slightly decreases when x < 0 and decreases greatly when x > 0. The Q x f value of the samples with x > 0 is much lower than that with x < 0. The maximum Q x f value of 70,917 GHz is obtained when x = -0.01. The temperature coefficient of resonant frequency exhibits positive value for the samples with x > 0 and negative value for the samples with x < 0. Near zero temperature coefficient of resonant frequency was obtained when x = 0.002. (C) 2006 Elsevier Ltd. All rights reserved.