Studies on Li3AlF6 thin film deposition utilizing conversion reactions of thin films

Miia Mäntymäki*, Kenichiro Mizohata, Mikko J. Heikkilä, Jyrki Räisänen, Mikko Ritala, Markku Leskelä

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

4 Citations (Scopus)

Abstract

The ternary lithium aluminum fluoride Li3AlF6 is formed from two optically interesting fluorides, LiF and AlF3. It has been reported to have a large electronic bandgap with a reasonable lithium-ion conductivity at room temperature, making it a potential electrolyte material for solid state lithium-ion batteries. Because of complications during attempts at direct atomic layer deposition of Li3AlF6, we have studied the deposition of the material using two conversion processes. In Process 1, a conversion reaction takes place when (Althd)3 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionate) and TiF4 are sequentially pulsed onto LiF films. The Li3AlF6 films contained LiF as an impurity phase, as determined with grazing incidence X-ray diffraction (GIXRD), and a large amount of titanium impurity, as determined with time-of-flight elastic recoil detection analysis (ToF-ERDA). In Process 2, AlF3 films are exposed to Lithd vapor, resulting in a conversion reaction that produced Li3AlF6 with some LiF. These films have also been studied with GIXRD and ToF-ERDA, and contained much smaller amounts of titanium and other impurities. The Li:Al metal ratios vary depending on the extent of Lithd exposure. Field emission scanning electron microscopy (FESEM) revealed that the Li3AlF6 films are quite porous.

Original languageEnglish
Pages (from-to)26-33
Number of pages8
JournalThin Solid Films
Volume636
DOIs
Publication statusPublished - 31 Aug 2017
MoE publication typeA1 Journal article-refereed

Keywords

  • Conversion reaction
  • Fluoride thin films
  • Lithium aluminum fluoride
  • Thin films

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