Effects of Ta2O5/Y2O3 Codoping on the Microstructure and Microwave Dielectric Properties of Ba(Co0.56Zn0.40)(1/3)Nb2/3O3 Ceramics

摘要

The effects of Ta2O5/Y2O3 codoping on the microstructure and microwave dielectric properties of Ba(Co0.56Zn0.40)(1/3)Nb2/3O3-xA-xB (A = 0.045 wt.% Ta2O5; B = 0.113 wt.% Y2O3) ceramics (x = 0, 1, 2, 4, 8, 16, 32) prepared according to the conventional solid-state reaction technique were investigated. The x-ray diffraction (XRD) results showed that the main crystal phase in the sintered ceramics was BaZn0.33Nb0.67O3-Ba3CoNb2O9. The additional surface phase of Ba8CoNb6O24 and trace amounts of Ba5Nb4O15 second phase were present when Ta2O5/Y2O3 was added to the ceramics. The 1:2 B-site cation ordering was affected by the substitution of Ta5+ and Y3+ in the crystal lattice, especially for x = 4. Scanning electron microscopy (SEM) images of the optimally doped ceramics sintered at 1340A degrees C for 20 h showed a compact microstructure with crystal grains in dense contact. Though the dielectric constant increased with the x value, appropriate addition would result in a tremendous modification of the Q x f and tau (f) values. Excellent microwave dielectric properties (epsilon (r) = 35.4, Q x f = 62,993 GHz, and tau (f) = 2.6 ppm/A degrees C) were obtained for the ceramic with x = 0.4 sintered in air at 1340A degrees C for 20 h.