**3. Conclusions**

The surprising anomaly in the diffusivity of a guest diffusing within the confined regions of a zeolite or a CNT or any other porous solid has many uses. It also explains the observed increase in ionic conductivity as a function of ionic radius on going from Li<sup>+</sup> to Na<sup>+</sup> to K<sup>+</sup> and Rb<sup>+</sup> and Cs+ [46]. Levitation effect was first observed in the experiments by Kemball and later Derouane showed its existence through theory [47–49]. It can be used in the separation of molecular mixtures as well as in separations of very high degree. Levitation effect can be better put into practice with single crystals and nano devices.

**Author details**

India

**69**

Shubhadeep Nag and Yashonath Subramanian\*

*Anomalous Diffusivity in Porous Solids: Levitation Effect*

*DOI: http://dx.doi.org/10.5772/intechopen.92685*

provided the original work is properly cited.

\*Address all correspondence to: yashonath@iisc.ac.in

Solid State and Structural Chemistry Unit, Indian Institute of Science, Bengaluru,

© 2020 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/ by/3.0), which permits unrestricted use, distribution, and reproduction in any medium,

### **Acknowledgements**

The authors wish to acknowledge support from Department of Science and Technology, New Delhi and computational facilities from Thematic Unit of Excellence for Computational Materials Science established with support from Nano Mission, DST, New Delhi.

*Anomalous Diffusivity in Porous Solids: Levitation Effect DOI: http://dx.doi.org/10.5772/intechopen.92685*
