Two novel low-firing germanates Li₂MGe₃O₈ (M = Ni, Co) microwave dielectric ceramics with spinel structure

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• 作者：Hao Luo^a ; Liang Fang^a ; ^{fanglianggl001@aliyun.com" class="auth_mail" title="E-mail the corresponding author} ; Huaicheng Xiang^a ; Ying Tang^a ; Chunchun Li^a ; ^b ; ^{lichunchun2003@126.com" class="auth_mail" title="E-mail the corresponding author}
• 关键词：Microwave dielectric properties ; Low-temperature cofired ceramics ; Germanate ; Spinel structure
• 刊名：Ceramics International
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：43
• 期：1
• 页码：1622-1627
• 全文大小：1580 K

文摘

Two low-firing ceramics Li₂MGe₃O₈ (M = Ni, Co) were prepared using the solid state reaction method and their microwave dielectric properties were characterized. X-ray diffraction analysis showed that both ceramics crystallized into a cubic spinel structure. Both ceramics were well densified at temperatures lower than 960 °C. Li₂NiGe₃O₈ ceramic sintered at 940 °C with relative density of ~95.2% obtained the optimum microwave dielectric properties with a relative permittivity (ε_r) ~8.6, a quality factor (Q×f) ~42,200 GHz (at 12.2 GHz), a temperature coefficient of resonance frequency τ_f ~ −78.2 ppm/°C. For Li₂CoGe₃O₈, the ceramic sintered at 950 °C had a relative density of 95.4%, a ε_r of 9.0, a Q×f of 40,500 GHz (at 12.6 GHz) and a τ_f of −42 ppm/°C. The negative τ_f values could be tuned by forming composite ceramics with rutile TiO₂. Chemical compatibility measurement indicates that both ceramics did not react with silver.