Towards understanding the special stability of ${\text{SrCo}\text{O}_{2.5}}$ and ${\text{HSrCo}\text{O}_{2.5}}$
| Autor: | Tsang, Sze-Chun, Zhang, Jingzhao, Tse, Kinfai, Zhu, Junyi |
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| Rok vydání: | 2018 |
| Předmět: | |
| Zdroj: | Phys. Rev. Materials 3, 024603 (2019) |
| Druh dokumentu: | Working Paper |
| DOI: | 10.1103/PhysRevMaterials.3.024603 |
| Popis: | Reversible hydrogen incorporation was recently attested [N. Lu, $\textit{et al.}$, Nature $\textbf{546}$, 124 (2017)] in ${\text{SrCo}\text{O}_{2.5}}$, the brownmillerite phase (BM) of strontium cobalt oxide (SCO), opening new avenues in catalysis and energy applications. However, existing theoretical studies of BM-SCO are insufficient, and that of ${\text{HSrCo}\text{O}_{2.5}}$, the newly-reported hydrogenated SCO (H-SCO), is especially scarce. In this work, we demonstrate how the electron-counting model (ECM) can be used in understanding the phases, particularly in explaining the stability of the oxygen-vacancy channels (OVCs), and in examining the Co valance problem. Using density-functional theoretical (DFT) methods, we analyze the crystalline, electronic, and magnetic structures of BM- and H-SCO. Based on our structure search, we discovered stable phases with large bandgaps (> 1 eV) for both BM-SCO and H-SCO, agreeing better with experiments on the electronic structures. Our calculations also indicate limited charge transfer from H to O that may explain the special stability of the H-SCO phase and the reversibility of H incorporation observed in experiments. In contrary to the initial study, our calculation also suggests intrinsic antiferromagnetism (AFM) of H-SCO, showing how the measured ferromagnetism (FM) has possible roots in hole doping. Comment: 9 pages, 10 figures, 4 tables + supplemental material; post-peer review version with amendments and additional contents |
| Databáze: | arXiv |
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