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A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties. Sintered at 960 ℃, the Ba2CuGe2O7 ceramic had a high relative density 97%, a low relative permittivity (εr) 9.43, a quality factor (Q×f) of 20,000 GHz, and a temperature coefficient of resonance frequency (τf) -76 ppm/℃. To get a deep understanding of the relationship between composition, structure, and dielectric performances, magnesium substitution for copper in Ba2CuGe2O7 was conducted. Influences of magnesium doping on the sintering behavior, crystal structure, and microwave dielectric properties were studied. Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure, grain morphology, and size distribution, while induced visible variation in the local structure as revealed by Raman analysis. Microwave dielectric properties exhibit a remarkable dependence on composition. On increasing the magnesium content, the relative permittivity featured a continuous decrease, while both the quality factor and the temperature coefficient of resonance frequency increased monotonously. Such variations in dielectric performances were clarified in terms of the polarizability, packing fraction, and band valence theory.


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A low-firing melilite ceramic Ba2CuGe2O7 and compositional modulation on microwave dielectric properties through Mg substitution

Show Author's information Changzhi YINa,cZezong YUbLonglong SHUbLaijun LIUcYan CHENaChunchun LIa,b,c( )
College of Information Science and Engineering, Guilin University of Technology, Guilin 541004, China
School of Materials Science and Engineering, Nanchang University, Nanchang 330031, China
Guangxi Universities Key Laboratory of Non-Ferrous Metal Oxide Electronic Functional Materials and Devices, College of Material Science and Engineering, Guilin University of Technology, Guilin 541004, China

† Changzhi Yin and Zezong Yu contributed equally to this work.

Abstract

A melilite Ba2CuGe2O7 ceramic was characterized by low sintering temperature and moderate microwave dielectric properties. Sintered at 960 ℃, the Ba2CuGe2O7 ceramic had a high relative density 97%, a low relative permittivity (εr) 9.43, a quality factor (Q×f) of 20,000 GHz, and a temperature coefficient of resonance frequency (τf) -76 ppm/℃. To get a deep understanding of the relationship between composition, structure, and dielectric performances, magnesium substitution for copper in Ba2CuGe2O7 was conducted. Influences of magnesium doping on the sintering behavior, crystal structure, and microwave dielectric properties were studied. Mg doping in Ba2CuGe2O7 caused negligible changes in the macroscopic crystal structure, grain morphology, and size distribution, while induced visible variation in the local structure as revealed by Raman analysis. Microwave dielectric properties exhibit a remarkable dependence on composition. On increasing the magnesium content, the relative permittivity featured a continuous decrease, while both the quality factor and the temperature coefficient of resonance frequency increased monotonously. Such variations in dielectric performances were clarified in terms of the polarizability, packing fraction, and band valence theory.

Keywords:

ceramics, dielectric properties, melilite structure, compositional modulation
Received: 22 June 2020 Revised: 06 September 2020 Accepted: 15 September 2020 Published: 25 November 2020 Issue date: February 2021
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Publication history
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Publication history

Received: 22 June 2020
Revised: 06 September 2020
Accepted: 15 September 2020
Published: 25 November 2020
Issue date: February 2021

Copyright

© The Author(s) 2020

Acknowledgements

This work was supported by National Natural Science Foundation of China (No. 62061011), National Key R&D Program of China (No. 2017YFB0406300), Natural Science Foundation of Guangxi Zhuang Autonomous Region (No. 2018GXNSFAA281253), and high-level innovation team and outstanding scholar program of Guangxi institutes.

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