BaTiO3-Based ceramics for tunable microwave applications
BaTiO3-Based ceramics for tunable microwave applications
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DOI：
10.1111/j.1551-2916.2004.01082.x
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发表时间：
2004-06-01
影响因子：
3.9
通讯作者：
Lanagan, MT
中科院分区：
文献类型：
--
作者：
Feteira, A;Sinclair, DC;Lanagan, MT
研究了传统固相法制备的BaTi0.09Ga0.05Nb0.05O3（BTGN）和Ba0.60Sr0.40TiO3（BST）陶瓷的介电性能。它们在微波（MW）可调谐应用中的相对潜力通过品质因数（K）来评估，品质因数（K）定义为K = λ（ro）-λ（rv）/λ（ro）（.）tan δ（o），（其中er和srv是10 kHz下0和20 kV cm（-1）时的相对介电常数，tan δ（o）是10 kHz或类似于1 GHz时的损耗，无直流偏置）。在空气中于1500 ℃下烧制的细晶粒（类似于2 -3 μ m）BTGN陶瓷表现出弛豫型材料的介电行为特征，在10 kHz和类似于1 GHz下，相对介电常数ε（r）分别从类似于3082降低到类似于2116，介电损耗tan δ分别从0.0035增加到0.0542。相比之下，大晶粒（20-100 μ m）BST陶瓷表现出与频率无关的ε（r）接近5000，并且tan δ随频率的变化很小（10 kHz时为0.0012，0.6 GHz时为0.0048）。在10 kHz时，K-BTGN = 91和K-BST = 367，而在MW频率时，K-BTGN = 6和K-BST = 92。MW频率下K-BTGN的大幅降低归因于tan δ的大幅增加。另一种弛豫型钛酸钡基陶瓷，Ba（Ti0.70Zr0.30）O-3，这是最近提出的可调MW应用程序的有前途的材料的适用性，也进行了讨论。结果表明，钛酸钡基铁电弛豫可能会表现出良好的可调特性在10 kHz，但是，他们没有竞争力的BST高K因子MW应用。
The dielectric properties of BaTi0.09Ga0.05Nb0.05O3 (BTGN) and Ba0.60Sr0.40TiO3 (BST) ceramics prepared by the conventional solid-state route have been investigated. Their relative potential for microwave (MW) tunable applications was assessed by the figure of merit (K) defined as K = epsilon(ro) - epsilon(rv)/epsilon(ro) (.) tan delta(o), (where er and srv are the relative permittivity at zero and 20 kV cm(-1) at 10 kHz and tan delta(o) is the loss at 10 kHz or similar to1 GHz without DC bias). Fine-grained (similar to2-3 mum) BTGN ceramics fired at 1500degreesC in air exhibit dielectric behavior characteristic of relaxor-type materials, with relative permittivity, epsilon(r), decreasing from similar to3082 to similar to2116 and dielectric loss, tan delta, increasing from 0.0035 to 0.0542 at 10 kHz and similar to1 GHz, respectively. In contrast, large-grained (20-100 mum) BST ceramics exhibit a frequency independent epsilon(r) of similar to5000 and show little variation of tan delta with frequency (0.0012 at 10 kHz and similar to0.0048 at 0.6 GHz). At 10 kHz, K-BTGN = 91 and K-BST = 367, whereas at MW frequencies K-BTGN = 6 and K-BST = 92. The large decrease in K-BTGN at MW frequencies is attributed to a substantial increase of tan delta. The applicability of another relaxor-type BaTiO3-based ceramic, Ba(Ti0.70Zr0.30)O-3, which was recently proposed as promising material for tunable MW applications, is also discussed. It is demonstrated that BaTiO3-based ferroelectric-relaxors may exhibit good tunable characteristics at 10 kHz; however, they are not competitive with BST for high K-factor MW applications.