Evidence for enormous iodide anion migration in lanthanum oxyiodide-based solid.

Imanaka, Nobuhito; Misran, Muhammad Radzi Iqbal Bin; Nunotani, Naoyoshi · Sci Adv · 2021

basic_science · Level V

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Abstract

The I<sup>−</sup> ion conduction was demonstrated and quantified in the La<sub>0.70</sub>Sr<sub>0.25</sub>Zn<sub>0.05</sub>OI<sub>0.70</sub> solid. The I<sup>−</sup> ion is considered to be an inferior conductor because of its large ionic size compared to the previously reported conducting ion species. Using modified Tubandt electrolysis, a weight increase at the anodic pellet and a corresponding weight decrease at the cathodic pellet were observed. The weight changes were in good agreement with the theoretical values estimated by considering pure I<sup>−</sup> ion migration. Furthermore, the iodine element appeared at the anode, and the iodine concentration at the cathode decreased after electrolysis, indicating that the migrating species was only I<sup>−</sup>. This is the first study to elucidate the conduction of iodide ions in solids.