Enhancement of densification and microwave dielectric properties in LiF ceramics via a cold sintering and post-annealing process

LIU, Bing, LI, Lei, SONG, Kai Xin, MAO, Min Min, LU, Zhilun, WANG, Ge, LI, Linhao, WANG, Dawei, ZHOU, Di, FETEIRA, Antonio and REANEY, Ian M (2020). Enhancement of densification and microwave dielectric properties in LiF ceramics via a cold sintering and post-annealing process. Journal of the European Ceramic Society.

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Official URL: https://www.sciencedirect.com/science/article/abs/...
Link to published version:: https://doi.org/10.1016/j.jeurceramsoc.2020.09.073

Abstract

LiF is a low-firing fluoride with excellent microwave dielectric properties, however densification of LiF ceramics is challenging owing to their low surface free energy. In this study, a cold sintering process (150 °C, 250 MPa, 60 min) was employed to pre-densify LiF ceramics to 78 % relative density. Post-annealing treatments between 650 °C and 800 °C led to significant grain growth which was accompanied by an increase in relative density to 92 %. The microwave quality factor (Qf) increased with increasing annealing temperature to a maximum of 110,800 GHz at 800 °C, 1.5 times higher than the value obtained via conventional sintering (78,800 GHz), with relative permittivity εr = 8.2 and temperature coefficient of resonant frequency, τf =–135 ppm/°C. Such high values of Qf and its compatibility with Ag electrode suggest that cold sintered LiF has great potential as a component or additive in low temperature co-fired ceramic formulations.

Item Type: Article
Uncontrolled Keywords: Materials; 0912 Materials Engineering
Identification Number: https://doi.org/10.1016/j.jeurceramsoc.2020.09.073
SWORD Depositor: Symplectic Elements
Depositing User: Symplectic Elements
Date Deposited: 21 Oct 2020 12:23
Last Modified: 04 Oct 2021 01:18
URI: https://shura.shu.ac.uk/id/eprint/27485

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