Energetics of atomic level serial ion exchange for cesium in micaceous clay minerals

Okumura, Masahiko   ; Nakamura, Hiroki  ; Machida, Masahiko  

We study interlayer cation exchanges between potassium and cesium ions in micaceous clay minerals by ab initio calculations using the density functional theory. The calculations reveal that the cesium exchange is energetically favored when the exchange neighbor sites are preoccupied by cesium, otherwise it is not so. This tendency is explained by the simple halide model, suggesting that the interlayer distance adjusted by serially occupied ion radius has a key role in the exchange stability.