Proton incorporations and superconductivity in a cobalt oxyhydrate

TL;DR

This study provides evidence of proton incorporation in a cobalt oxyhydrate superconductor, revealing how hydration alters its composition and superconducting properties at low temperatures.

Contribution

It demonstrates proton incorporation during hydration and characterizes the resulting compound's composition and superconductivity.

Findings

Proton incorporation occurs during hydration of Na$_{0.32}$CoO$_{2}$.

The resulting compound is Na$_{0.22}$H$_{0.1}$CoO$_{2}\

0.85\

Abstract

We report the evidence of proton incorporations in a newly-discovered cobalt oxyhydrate superconductor. During the hydration process for Na$_{0.32}$CoO$_{2}$ by the direct reaction with water liquid, it was shown that substantial NaOH was gradually liberated, indicating that H$^{+}$ is incorporated into the hydrated compound. Combined with the thermogravimetric analysis, the chemical composition of the typical sample is Na$_{0.22}$H$_{0.1}$CoO$_{2}\cdot 0.85$H$_{2}$O, which shows bulk superconductivity at 4.4 K.