Control of nitrogen concentration in liquid lithium by hot trapping

Nitrogen concentration in liquid lithium was controlled by the method of hot trapping. V–Ti alloy and chromium were used as nitrogen gettering materials. Chromium is known to form ternary nitride with lithium. Gettering experiments were conducted at 823 K for 0.8–2.2 Ms. Under high nitrogen concentration in liquid lithium, above 10−2 mass%, nitrogen gettering effect of chromium was found to be larger than that of V–10at.% Ti alloy. Nitrogen gettering by chromium at 823 K reached a limit at about 6.5×10−3 mass% of nitrogen concentration in liquid lithium. Instability of ternary nitride of chromium and lithium below this nitrogen concentration in liquid lithium was considered to be the reason for this limit. The composition of the ternary nitride that was formed in this study was considered to be Li6Cr(III)3N5. In addition, immersion experiments of yttrium with V–10at.% Ti alloy were performed. It was found that nitriding of yttrium in liquid lithium is controlled by nitrogen gettering effect of V–10at.% Ti alloy.