Flash sintering of high bandgap halides triggered by electrochemical reduction

We have studied the flash sintering behavior of high bandgap ceramics (halides) namely Lithium Fluoride (LiF), Magnesium Fluoride (MgF2), and Sodium Chloride (NaCl). All three halides demonstrate flash sintering behavior albeit at elevated temperatures of ∼0.8 homologous temperature and a very high...

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Bibliographic Details
Published in:Ceramics international 2024-07, Vol.50 (13), p.23076-23087
Main Authors: Raj, Rohit, Eqbal, Ammar, Arya, Kumar Sadanand, Singh, Shubham Kumar, Chakrabarti, Tamoghna
Format: Article
Language:English
Subjects:
Band gap
Electrochemical reaction
Electromigration
Electronic conduction
Flash sintering
Halide
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Summary:We have studied the flash sintering behavior of high bandgap ceramics (halides) namely Lithium Fluoride (LiF), Magnesium Fluoride (MgF2), and Sodium Chloride (NaCl). All three halides demonstrate flash sintering behavior albeit at elevated temperatures of ∼0.8 homologous temperature and a very high electric field. The achieved relative densities after flash sintering are 89 % for LiF, 88 % for MgF2, and 96 % for NaCl. Conductivity-temperature plots reveal a likely transition from ionic conduction to electronic conduction, exemplified by a substantial decrease in activation energy. Interestingly, despite their high bandgaps, the halides exhibit flash sintering and electronic conduction at the flash state. However, electronic conduction likely occurs due to electrochemical reduction. Evidence of electromigration is observed near the grain boundary triple points. This work also shows a likely correlation between band gap/electrode potential and onset electric field/homologous temperature during flash sintering for the first time.
ISSN:0272-8842
1873-3956
DOI:10.1016/j.ceramint.2024.04.030