Tunable high Q perovskite dielectrics in the BaO–NiO–Ta2O5 system
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Oxide perovskites with the general formula A(B 1/3IB 2/3II)O 3 (A = Ba, Sr; B I = Mg, Zn, Ni, Co, etc.; B II = Ta, Nb) have been investigated for over two decades for applications as dielectric resonators in wireless communication systems. The key materials requirements include a high dielectric constant (ε), low dielectric loss or high quality factor ( Q) in the GHz range, and a zero temperature coefficient of resonant frequency (τ f). Recent investigations of the effect of Zn volatilization on the properties of one of the most studied high Q systems, Ba(Zn 1/3Ta 2/3)O 3 (BZT), revealed a resultant Zn-deficient impurity phase, Ba 8ZnTa 6O 24 also exhibits a good microwave response (ε = 30.5, Q· f = 62,000, τ f = +36 ppm/°C) [ 1, 2, 3]. This phase, which has a closely related hexagonal perovskite structure (Fig. 1), can also be sintered at temperatures significantly lower than its cubic perovskite counterpart.
KeywordsPerovskite Dielectric Property Microwave Dielectric Property Standard Solid State Hexagonal Perovskite
This work was supported by Ericsson Radio Access and made use of the MRSEC shared experimental facilities supported by the National Science Foundation through Grant No. DMR 05-20020.
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