Crystal structure and microwave dielectric characteristics of Zr-substituted CoTiNb₂O₈ ceramics

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• 作者：Yun Zhang ; Yingchun Zhang ; ^{zycustb@163.com" class="auth_mail" title="E-mail the corresponding author} ; ^{zhang@ustb.edu.cn" class="auth_mail" title="E-mail the corresponding author} ; Maoqiao Xiang
• 关键词：Co(Ti1-xZrx)Nb2O8 ceramic ; Sintering ; Crystal structure ; Microwave dielectric property
• 刊名：Journal of the European Ceramic Society
• 出版年：2016
• 出版时间：July 2016
• 年：2016
• 卷：36
• 期：8
• 页码：1945-1951
• 全文大小：2890 K

文摘

Co(Ti_1-xZr_x)Nb₂O₈ microwave dielectric ceramics were synthesized via the conventional solid-state reaction route. The dependence of microwave dielectric properties on the crystal structure was discussed. The phase transitions were analyzed using X-ray powder diffraction, Raman spectroscopy, and transmission electron microscopy. A series of composition-induced phase transitions were confirmed via the sequence: tetragonal rutile structure → coexistence of rutile and wolframite phase → monoclinic wolframite structure. For the Co(Ti_1-xZr_x)Nb₂O₈ compounds, Zr substitutions from 0 to 1 led to a decrease in the ε_r from 62.4 to 23.8. In contrast to ε_r, Q × f increased considerably, which was explained in terms of packing fraction. The τ_f was correlated with oxygen octahedral distortion and B-site bond valence. A near zero τ_f of 4.4 ppm/°C was obtained in the CoTi_0.4Zr_0.6Nb₂O₈ ceramics with an ε_r of 29.9 and a high Q × f of 72,833 GHz.