Microwave Dielectric Ceramics in Li2O–Bi2O3–MoO3 System with Ultra-Low Sintering Temperatures
Microwave Dielectric Ceramics in Li2O–Bi2O3–MoO3 System with Ultra-Low Sintering Temperatures
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DOI：
10.1111/j.1551-2916.2009.03526.x
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发表时间：
2010-04
影响因子：
3.9
通讯作者：
Di Zhou;C. Randall;Hong Wang;L. Pang;X. Yao
中科院分区：
文献类型：
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作者：
Di Zhou;C. Randall;Hong Wang;L. Pang;X. Yao
研究了Li2O-Bi2O3-MoO3三元系化合物的制备、物相组成、微波介电性能及其与银、铝电极的化学兼容性。本文重点研究了Li2MoO4、(Li0.5Bi0.5)MoO4和Li8Bi2Mo7O28三种单相陶瓷的烧结行为和微波介电性能。(Li0.5Bi0.5)MoO4陶瓷具有白钨矿结构，其相对介电常数为∼+245ppm/°C，相对介电常数为+245ppm/°C，相对介电常数为+245ppm/°C，(Li0.5Bi0.5)MoO4陶瓷为白钨矿结构，相对介电常数为44.4，相对介电常数为13.6，Q×f值为8000 GHz，相对介电常数为13.6，相对介电常数∼−为8000 GHz。∼−为59ppm/°C。从共烧陶瓷的X射线衍射分析可知，Li2MoO4陶瓷不与银粉或铝粉发生反应。在致密化温度下，Li8Bi2Mo7O28陶瓷与Ag发生反应，与Al不发生反应。发现(Li0.5Bi0.5)MoO4陶瓷与银粉发生强烈反应，与铝粉发生有限的反应。研究表明，Li2O-Bi2O3-MoO_3三元系具有烧结温度低、高性能微波介电性能、与金属银和铝电极的化学兼容性、无毒和低成本等一系列诱人的新材料。所有这些材料都可以纳入多层应用的超低温共烧介质的新领域。
A series of compounds in the Li2O–Bi2O3–MoO3 ternary system were investigated with regard to the preparation, phase composition, microwave dielectric properties, and chemical compatibility with silver (Ag) and aluminum (Al) electrodes. All the ceramics in this work have sintering temperatures lower than 750°C. The sintering behaviors and microwave dielectric properties of three single phases Li2MoO4, (Li0.5Bi0.5)MoO4, and Li8Bi2Mo7O28 bulk ceramics, were of particular focus in this investigation. The Li2MoO4 ceramic can be sintered to a high density at 540°C/2 h with a relative permittivity ∼5.5, a Q×f value of 46 000 GHz, and a temperature coefficient of resonant frequency (TCF) of ∼−160 ppm/°C. The (Li0.5Bi0.5)MoO4 ceramic has a scheelite structure and the largest relative permittivity of 44.4 among the ceramics studied in this work with a sintering temperature around 560°C, a Q×f value of 3200 GHz, and a large positive TCF of ∼+245 ppm/°C. The Li8Bi2Mo7O28 ceramic could be sintered at 540°C and has a relative permittivity of 13.6, a Q×f value of 8000 GHz, and a small negative TCF value of ∼−59 ppm/°C. From the X-ray diffraction analysis of cofired ceramics, the Li2MoO4 ceramic does not react with either Ag or Al powders. The Li8Bi2Mo7O28 ceramic reacts with Ag but not with Al at its densification temperature. The (Li0.5Bi0.5)MoO4 ceramic was found to strongly react with Ag powder and to a limited extent with Al powders. From this study, the Li2O–Bi2O3–MoO3 ternary system has a number of attractive new materials with low sintering temperatures, high-performing microwave dielectric properties, chemical compatibility with both Ag and Al metal electrodes, nontoxicity, and low-cost constituents. All these materials can be included in the new field of ultra-low-temperature cofiring dielectrics for multilayer applications.