Low‐temperature sintering and thermal stability of Li₂GeO₃‐based microwave dielectric ceramics with low permittivity
Yin, Changzhi; Xiang, Huaicheng; Li, Chunchun; Porwal, Harshit; Fang, Liang (2018-04-25)
Yin C, Xiang H, Li C, Porwal H, Fang L. Low‐temperature sintering and thermal stability of Li2GeO3‐based microwave dielectric ceramics with low permittivity. J Am Ceram Soc. 2018;101:4608–4614. https://doi.org/10.1111/jace.15723
© 2018 The American Ceramic Society. This is the peer reviewed version of the following article: Yin C, Xiang H, Li C, Porwal H, Fang L. Low‐temperature sintering and thermal stability of Li2GeO3‐based microwave dielectric ceramics with low permittivity. J Am Ceram Soc. 2018;101:4608–4614. https://doi.org/10.1111/jace.15723, which has been published in final form at https://doi.org/10.1111/jace.15723. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Self-Archiving.
A low‐permittivity dielectric ceramic Li₂GeO₃ was prepared by the solid‐state reaction route. Single‐phase Li₂GeO₃ crystallized in an orthorhombic structure. Dense ceramics with high relative density and homogeneous microstructure were obtained as sintered at 1000‐1100°C. The optimum microwave dielectric properties were achieved in the sample sintered at 1080°C with a high relative density ~ 96%, a relative permittivity εr ~ 6.36, a quality factor Q × f ~ 29 000 GHz (at 14.5 GHz), and a temperature coefficient of resonance frequency τf ~ −72 ppm/°C. The sintering temperature of Li₂GeO₃ was successfully lowered via the appropriate addition of B₂O₃. Only 2 wt.% B₂O₃ addition contributed to a 21.2% decrease in sintering temperature to 850°C without deteriorating the dielectric properties. The temperature dependence of the resonance frequency was successfully suppressed by the addition of TiO₂ to form Li₂TiO₃ with a positive τf value. These results demonstrate potential applications of Li₂GeO₃ in low‐temperature cofiring ceramics technology.
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