Solubility of Nitrogen and Oxygen in Lithium and Methods of Lithium Purification
SourceNitrogen and oxygen are two of the most common impurities found in commercially available lithium. Experiments were conducted to determine the solubility of these elements in lithium in the temperature range from 250 to 450 C and to determine which of several possible purification methods was most effective in reducing the nitrogen and oxygen content of lithium. The solubility of nitrogen in lithium increased from 0.04 per cent by weight at 250 C to 1.31 per cent by weight at 450 C. The solubility of oxygen was found to be 0.010 per cent by weight at 250 C and increased to 0.066 per cent by weight at 400 C. Vacuum distillation, low-temperature filtration, cold-trapping, and gettering with active metals were investigated as possible purification methods to reduce the nitrogen and oxygen content of lithium. Of the techniques studied, gettering with active metals was found to be the most effective method of reducing the nitrogen concentration, while cold-trapping and low-temperature filtration were most effective in reducing the oxygen concentration.