Sintering behavior and mechanism of Bi-Zn-Nb-O microwave dielectric ceramics

Bi-Zn-Nb-O-based microwave dielectric ceramics are promising candidates for wireless communication. Investigations have concentrated on their fabrication methods and doping modification. In this work, the densification mechanism and grain growth kinetics of the Bi-Zn-Nb-O-based microwave dielectric ceramics were explored. A significantly wide sintering temperature window (800-1000 degrees C) of the monoclinic Bi2Zn2/3Nb4/3O7 (BZN) was found. High-density stacking faults were observed in BZN grains at the initial stage of sintering, which could act as paths for mass transport, thus remarkably accelerating the densification process and decreasing the densification temperature. On the other hand, BZN possesses a high grain growth exponent and activation energy, which indicates a slow grain growth rate and a high threshold for abnormal grain growth, corresponding to the wide sintering temperature window. Moreover, the BZN ceramics display good microwave dielectric properties stability over a wide temperature range (25-450 degrees C).