Influence of Non‐Stoichiometry on the Structure and Properties of Ba(Zn _1/3 Nb _2/3 )O ₃ Microwave Dielectrics: II. Compositional Variations in Pure BZN

Abstract

The formation of non‐stoichiometric cubic perovskite solid solutions based on BaZn 1/3 Nb 2/3 O 3 (BZN) was examined along 10 different directions in the BaO–ZnO–Nb 2 O 5 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 × f s (∼110 000 at 8 GHz) in the system, which coincide with the highest degree of order, were located in two regions along the BZN–Ba 5 Nb 4 O 15 and BZN–BaNb 2 O 6 lines. The results of this study provide an explanation for the large variations in crystal structure and Q × f s previously reported for BZN and other related systems (e.g., Ba(Zn 1/3 Ta 2/3 )O 3 ), and demonstrate that non‐stoichiometric starting compositions provide a route to the highest Q values.