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The formation of non-stoichiometric cubic perovskite solid solutions based on BaZn1/3Nb2/3O3 (BZN) was examined along 10 different directions in the BaO–ZnO–Nb2O5 ternary system. Limited ranges of non-stoichiometry were observed along several pseudo-binaries and the BZN structure can accommodate a variety of different types of defects. Although the deviations from stoichiometry are quite small, typically ~1 mole%, they induce large changes in the extent and stability of the 1:2 B-site ordering, the sintering and microstructure, and the dielectric loss properties. The highest Q×fs (~110 000 at 8 GHz) in the system, which coincide with the highest degree of order, were located in two regions along the BZN–Ba5Nb4O15 and BZN–BaNb2O6 lines. The results of this study provide an explanation for the large variations in crystal structure and Q×fs previously reported for BZN and other related systems (e.g., Ba(Zn1/3Ta2/3)O3), and demonstrate that non-stoichiometric starting compositions provide a route to the highest Q values.
Date Posted: 05 December 2006
This document has been peer reviewed.