Cesium Diffusion Through Angstrom-Scale Open Spaces In Clay Minerals

Saponite clay minerals possess the local molecular structures, where one and two nanosheets are inserted into interlayer spaces forming open spaces with their sizes of similar to 3 and similar to 9 angstrom, respectively. Here, Cs diffusion via the abovementioned open spaces is highlighted based on the results of open space analysis using positronium (Ps) lifetime spectroscopy coupled with a conventional diffusion experiment. A population of Cs is found to significantly migrate in the saponite clay yielding a diffusion coefficient of similar to 2.0 x 10(-7) cm(2) s(-1) with an application of Fick's second law, which arises from overall diffusion contributed from open spaces with a variety of sizes. On the other hand, the diffusion coefficient solely attributable to the angstrom-scale open space is similar to 2.5 x 10(-8) cm(2) s(-1), which amounts to more than similar to 10% than that of overall diffusion.