六方晶形硝酸ナトリウム-硝酸銀固溶体と硝酸ナトリウム飽和水溶液の間の微量元素の分配 –アルカリ金属イオンの分配係数に及ぼす銀の影響

抄録

Partition coefficients of Ag⁺, Li⁺, K⁺, and Rb⁺ between sodium nitrate and its saturated solution at 25°C were determined to be 0.33, 9.5x10^-3, 3.6x10^-3, and 1.2x10^-4, respectively. A linear relationship was found between logarithms of partition coefficients of these elements (except lithium) and squares of differences in ionic radii. The calculated coefficients of these elements on the basis of Nagasawa's theory did not coincide with the observed ones as in the case of the partition between sodium nitrate and its melt. Partition coefficient of potassium varies with silver concentration of solid NaNO₃. It takes a maximum value at the concentration of about 2 mol percent of silver. On the contrary, coefficient of potassium (and perhaps of rubidium) does not take any such maximum value, but shows only a small decrease in its value with an increase in the concentration of silver. The difference in partition patterns of these elements has been elucidated by an elastic model for substitution of trace elements in ionic crystals.