• Deterioration of hydrogen-bonded superprotonic conductors belonging to CsHSO$_4$–CsH$_2$PO$_4$–H$_2$O salt system: a single-crystal neutron diffraction investigation

• # Fulltext

https://www.ias.ac.in/article/fulltext/boms/044/0108

• # Keywords

Hydrogen bonding; neutron diffraction; proton conductors.

• # Abstract

Single-crystal neutron diffraction investigation on Cs$_4$(HSO$_4$)$_3$(H$_2$PO$_4$) and Cs$_6$H(HSO$_4$)$_3$(H$_2$PO$_4$)$_4$ superprotonic crystals, belonging to CsHSO$_4$–CsH$_2$PO$_4$–H$_2$O salt system, is under taken to elucidate the precise hydrogen atom positions in these crystals. The investigation revealed that these crystals are very sensitive to the ambient conditions and can undergo deterioration due to fluctuation in air moisture content. Cs$_6$H(HSO$_4$)$_3$(H$_2$PO$_4$)$_4$ crystals are more stable as compared to Cs$_4$(HSO$_4$)$_3$(H$_2$PO$_4$). Crystal structure of Cs$_6$H(HSO$_4$)$_3$(H$_2$PO$_4$)$_4$ is obtained both before and after deterioration,it is found that the asymmetric O–HO hydrogen bond between the PO$_4$ and SO$_4$ ions of this crystal becomes stronger after deterioration. This led to the shrinkage of the unit cell, and most likely prevented further deterioration. Diabatic state model for hydrogen bonds is used to obtain the energy contour for the O–H$\ldots$O hydrogen bond of Cs$_6$H(HSO$_4$)$_3$(H$_2$PO$_4$)$_4$ crystal. The influence of this change in the hydrogen bonding on the proton conduction ability ofthe crystal is discussed.

• # Author Affiliations

1. Solid State Physics Division, Bhabha Atomic Research Center, Mumbai 400085, India
2. Shubnikov Institute of Crystallography of Federal Scientific Research Centre, 'Crystallography and Photonics' of Russian Academy of Sciences, Moscow, Russia

• # Bulletin of Materials Science

Volume 45, 2022
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• # Dr Shanti Swarup Bhatnagar for Science and Technology

Posted on October 12, 2020

Prof. Subi Jacob George — Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bengaluru
Chemical Sciences 2020

Prof. Surajit Dhara — School of Physics, University of Hyderabad, Hyderabad
Physical Sciences 2020

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