Effect of CuO-based Oxide Additives on Bi2O3–ZnO–Nb2O5 Microwave Ceramics

概要

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Different kinds of CuO–MOx mixtures were used to investigate their role in the microstructure evolution, sintering densification and microwave properties of Bi2(Zn1/3Nb2/3)2O7 (BZN) ceramics. Without the addition of CuO–MOx mixtures, pure BZN ceramics have to be sintered above 900°C. However, a comparable bulk density to that of pure BZN ceramics sintered at 950°C can be achieved for 2 wt% 0.29BaCO3–0.71CuO-added at 850°C and 0.15CuO–0.85MoO3-added BZN ceramics at 800°C, which was attributed to the liquid-phase sintering. A higher dielectric constant along with a smaller $Q$ factor was obtained in 0.29BaCO3–0.71CuO-added BZN ceramics because of the formation of the BaBi2Nb2O9 phase. On the other hand, a larger $Q$ factor of $\sim 1500$ can be obtained at about 850°C for 1 wt% 0.15CuO–0.85MoO3-added BZN ceramics. However, as the 0.2CuO–0.8GeO2 mixture was used, a partial transformation of pseudo-tetragonal Bi2(Zn1/3Nb2/3)2O7 to cubic (Bi1.5Zn0.5)(Zn0.5Nb1.5)O7 phase was induced possibly because both Zn2+ and Ge4+ have similar ion radius and electronegativity. With increasing 0.2CuO–0.8GeO2 content, a decrease in microwave properties was also obtained due to an inhibition of sintering densification since a eutectic liquid phase was not formed.
INSTITUTE OF PURE AND APPLIED PHYSICSの論文
2001-05-15