Synthesis and microwave dielectric properties of Bi₂Ge₃O₉ ceramics for application as advanced ceramic substrate

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• 作者：Xing-Hua Ma^a ; Sang-Hyo Kweon^a ; Sahn Nahm^a ; ^b ; ^c ; ^{snahm@korea.ac.kr" class="auth_mail" title="E-mail the corresponding author} ; Chong-Yun Kang^b ; ^c ; Seok-Jin Yoon^c ; Young-Sik Kim^d
• 关键词：Bi2Ge3O9 ceramics ; LTCC ; Microwave dielectric properties ; Advanced ceramic substrates
• 刊名：Journal of the European Ceramic Society
• 出版年：2017
• 出版时间：February 2017
• 年：2017
• 卷：37
• 期：2
• 页码：605-610
• 全文大小：1724 K

文摘

During the synthesis of Bi₂Ge₃O₉ ceramics using Bi₂O₃ + 3GeO₂ powders, the Bi₄Ge₃O₁₂ phase was formed at low temperature (≤800 °C). Bi₄Ge₃O₁₂ preferentially adopted GeO₂-excess phase, and this phase was consistently present in the sintered Bi₂Ge₃O₉ ceramic as a secondary phase. Therefore, Bi₄Ge₃O₁₂ powder was first calcined and subsequently reacted with GeO₂ powder to obtain the pure Bi₂Ge₃O₉ ceramic through the following reaction: 1/2Bi₄Ge₃O₁₂ + 3/2GeO₂ → Bi₂Ge₃O₉. Formation of the Bi₂Ge₃O₉ phase was initiated at temperature of 850 °C. The pure Bi₂Ge₃O₉ ceramic sintered at 875 °C for 8 h had a dense microstructure with an average grain size of 2.7 μm. Furthermore, the pure Bi₂Ge₃O₉ ceramic exhibited promising microwave dielectric properties for the advanced ceramic substrate: ε_r = 9.7, Q × f = 48,573 GHz and τ_f = −29.5 ppm/°C.