Structure and Microwave Dielectric Properties of Ca_1−xY_xTi_1−xAl_xO_3 (CYTA) Ceramics
Structure and Microwave Dielectric Properties of Ca_1−xY_xTi_1−xAl_xO_3 (CYTA) Ceramics
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DOI：
10.1557/jmr.2005.0289
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发表时间：
2005-09
影响因子：
2.7
通讯作者：
A. Feteira;D. Sinclair;M. Lanagan
中科院分区：
文献类型：
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作者：
A. Feteira;D. Sinclair;M. Lanagan
研究了混合氧化物法制备的Ca_1− xY_xTi_1 − xAl_xO_3（CYTA）陶瓷的结构和介电性能。CYTA形成具有正交钙钛矿结构的完全固溶体。在0.9左右，观察到反应不完全产生的Y_4Al_2O_9和Y_3Al_5O_（12）。扫描电子显微镜显示，CYTA陶瓷具有均匀的显微结构，平均晶粒尺寸从x = 0时的1.200 μm减小到x = 1.0时的1.10 μm。CYTA（x = 0.3）陶瓷的透射电子显微镜显示存在铁弹畴，电子衍射图案在Pnma空间群上索引，与a ^+ B ^− B ^−八面体倾斜结构一致。当x = 0和1时，相对介电常数ε r从170连续减小到12，而微波品质因数Q·fr从10，000增加到12，000 GHz。CYTA（x = 0.30）陶瓷的介电常数为38，Q·f _r为14，212 GHz，谐振频率温度系数τ_f为−14 ppm/°C。少量的受主（0.3wt%ZnO）或施主（1wt%Nb_2O_5）掺杂使Q·fr分别降低约20- 30%。
The structure and dielectric properties of Ca_1− x Y_xTi_1− x Al_xO_3 (CYTA) ceramics prepared by the mixed-oxide route have been investigated. CYTA forms a complete solid solution with an orthorhombic perovskite structure. Residual Y_4Al_2O_9 and Y_3Al_5O_12 resulting from incomplete reaction are observed for ⩾ 0.9. Scanning electron microscopy shows that CYTA ceramics exhibit uniform microstructures, with an average grain size that decreases from ∼200 μm at x = 0 to ∼10 μm at x = 1.0. Transmission electron microscopy of CYTA ( x = 0.3) ceramics reveals the presence of ferroelastic domains, and electron-diffraction patterns are indexed on the Pnma space group, consistent with an a ^+ b ^− b ^− octahedral tilted structure. The relative permittivity, ϵ_r, decreases continuously from 170 to 12, while the microwave quality factor, Q·f _r, increases from 10,000 to 12,000 GHz, for x = 0 and 1, respectively. CYTA ( x = 0.30) ceramics exhibit ϵ_r ∼ 38, Q·f _r of ∼14,212 GHz, and a temperature coefficient of resonance frequency, τ_f, of −14 ppm/°C. Small additions of acceptor (0.3 wt% ZnO) or donor (1 wt% Nb_2O_5) dopants decrease Q·f _r by ∼20-30%, respectively.