Synergistic regulation of the formation of yttrium oxyfluoride layer on yttrium oxide substrate by fluoride-chloride molten salts.

Fluoride molten salt (KAlF 4) can modify Y 2 O 3 to form YOF, but the reaction degree of this process is difficult to control and tends to form a large amount of yttrium fluoride (YF 3) with low-strength. The reaction degree of the modification process of fluoride molten salt with Y 2 O 3 can be suppressed by the synergistic effect of chlorides (KCl-CaCl 2), which is mainly determined by the diffusion of fluorine-containing complex ions (AlF 4 -) in the fluoride-chloride mixed molten salts (FCMMS). The low diffusion rate of AlF 4 - in FCMMS directly leads to the decrease of the fluorination reaction rate and delays or even prevents the deeper fluorination process. After the synergistic modulation of Y 2 O 3 by FCMMS, only YOF is formed, and the formation of YF 3 is completely avoided. The strategy and mechanism may be applied to the economical preparation of YOF protective layer or YOF powder on low-cost Y 2 O 3 template. [ABSTRACT FROM AUTHOR]