Microwave dielectric properties of novel glass-free low temperature firing ACa₂Mg₂V₃O₁₂ (A=Li, K) ceramics

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• 作者：Hao Luo^a ; Weishuang Fang^a ; Liang Fang^a ; ^c ; ^{fanglianggl001@aliyun.com" class="auth_mail" title="E-mail the corresponding author} ; Wei Li^c ; Chunchun Li^a ; ^b ; ^{lichunchun2003@126.com" class="auth_mail" title="E-mail the corresponding author} ; Ying Tang^a
• 关键词：Microwave dielectric properties ; Garnet ; Vanadate
• 刊名：Ceramics International
• 出版年：2016
• 出版时间：June 2016
• 年：2016
• 卷：42
• 期：8
• 页码：10506-10510
• 全文大小：1549 K

文摘

Two novel low-firing microwave dielectric ceramics ACa₂Mg₂V₃O₁₂ (A=Li, K) were prepared using the solid state reaction method. The phase composition, sintering behavior, and microwave dielectric properties were investigated. X-ray diffraction (XRD) analysis showed that both ceramics crystallized into a cubic garnet structure. Both ceramics were well densified at temperatures lower than 960 °C. LiCa₂Mg₂V₃O₁₂ ceramic sintered at 940 °C with relative density of ~96.3% obtained the optimum microwave dielectric properties with ε_r ~9.8, Q×f ~24,900 GHz (at 11.0 GHz), τ_f ~+259.2 ppm/°C. For KCa₂Mg₂V₃O₁₂, the ceramic sintered at 900 °C had a relative density of ~96.1%, a relative permittivity (ε_r) ~10, a quality factor (Q×f) ~30,330 GHz and a large positive temperature coefficient of resonance frequency τ_f ~+190.9 ppm/°C. Both ACa₂Mg₂V₃O₁₂ (A=Li, K) ceramics were chemically compatible with Ag electrodes. The large positive τ_f of LiCa₂Mg₂V₃O₁₂ ceramic could be compensated by forming sold solution with NaCa₂Mg₂V₃O₁₂, and improved properties with a near-zero τ_f=+2 ppm/°C, ε_r=9.9, Q×f=45,500 GHz was obtained for 0.16LiCa₂Mg₂V₃O₁₂–0.84NaCa₂Mg₂V₃O₁₂ ceramic sintered at 920 °C for 4 h.