Defect Trapping and Phase Separation in Chemically Doped Bulk AgF2

Adam Grzelak; Mariana Derzsi; Wojciech Grochala

doi:10.1021/acs.inorgchem.0c02970

Defect Trapping and Phase Separation in Chemically Doped Bulk AgF₂

Inorg Chem. 2021 Feb 1;60(3):1561-1570. doi: 10.1021/acs.inorgchem.0c02970. Epub 2021 Jan 19.

Authors

Adam Grzelak¹, Mariana Derzsi^{1

2}, Wojciech Grochala¹

Affiliations

¹ Center of New Technologies, University of Warsaw, Banacha 2C, 02-097 Warsaw, Poland.
² Advanced Technologies Research Institute, Faculty of Materials Science and Technology in Trnava, Slovak University of Technology in Bratislava, Jána Bottu 8857/25, 917 24 Trnava, Slovakia.

Abstract

We report a computational survey of chemical doping of silver(II) fluoride, which has recently attracted attention as an analogue of La₂CuO₄-a known precursor of high-temperature superconductors. By introducing fluorine defects (vacancies or interstitial adatoms) into the crystal structure, we obtain nonstoichiometric, electron- and hole-doped polymorphs of AgF_2±x. We find that the ground-state solutions show a strong tendency for localization of defects and of the associated electronic states, and the resulting doped phases exhibit insulating or semiconducting properties. Furthermore, the distribution of Ag(I)/Ag(III) sites which appear in the crystal structure points to the propensity of the AgF₂ system for phase separation upon chemical doping, which is in line with observations from previous experimental attempts. Overall, our results indicate that chemical modification may not be a feasible way to achieve doping in bulk silver(II) fluoride, which is considered essential for the emergence of high-T_c superconductivity.