Electride States and Superconductivity in Dense Potassium Carbides
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arXiv
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| Natura: | Preprint |
| Pubblicazione: |
2026
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| _version_ | 1866917537785053184 |
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| author | Sun, Jiance Zhong, Ting Zhang, Shoutao |
| author_facet | Sun, Jiance Zhong, Ting Zhang, Shoutao |
| contents | Metal carbides have attracted a great deal of attention due to their diverse geometric motifs, remarkable physicochemical properties, and widespread practical applications. However, there is still a lack of systematic understanding regarding the phase diagram of pressurized potassium carbide. Employing first-principles swarm-intelligence structure prediction approach, we comprehensively explore the binary potassium-carbon phases under compression and identify a series of new K-rich and C-rich stoichiometric compounds. Among them, K7C with high K concentration manifests a monoclinic structure with space group C2/m and is predicted to be an electride with zero-dimensional (0D) interstitial electrons. C-abundant KC has an orthorhombic configuration with symmetry Imma, with the carbon atoms arranged in a zigzag pattern. Strikingly, KC3, belonging to a monoclinic C2/m structure, possesses the highest carbon content and features a crumpled honeycomb carbon layer. Furthermore, calculations of electron-phonon coupling reveals that K7C is a 0D electride superconductor with a transition temperature (Tc) of 0.6 K at a pressure of 25 GPa. By contrast, KC exhibits a maximum Tc of 21.4 K at 25 GPa, which is primarily attributed to the robust coupling between low-frequency K- and C-derived phonon modes and C 2p electrons at the Fermi level. In addition, KC3 is calculated to have a Tc value of 6.7 K at 25 GPa. This study provides valuable insights into K-C compounds and broadens the diversity of metal carbide superconductors. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2605_27201 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Electride States and Superconductivity in Dense Potassium Carbides Sun, Jiance Zhong, Ting Zhang, Shoutao Superconductivity Metal carbides have attracted a great deal of attention due to their diverse geometric motifs, remarkable physicochemical properties, and widespread practical applications. However, there is still a lack of systematic understanding regarding the phase diagram of pressurized potassium carbide. Employing first-principles swarm-intelligence structure prediction approach, we comprehensively explore the binary potassium-carbon phases under compression and identify a series of new K-rich and C-rich stoichiometric compounds. Among them, K7C with high K concentration manifests a monoclinic structure with space group C2/m and is predicted to be an electride with zero-dimensional (0D) interstitial electrons. C-abundant KC has an orthorhombic configuration with symmetry Imma, with the carbon atoms arranged in a zigzag pattern. Strikingly, KC3, belonging to a monoclinic C2/m structure, possesses the highest carbon content and features a crumpled honeycomb carbon layer. Furthermore, calculations of electron-phonon coupling reveals that K7C is a 0D electride superconductor with a transition temperature (Tc) of 0.6 K at a pressure of 25 GPa. By contrast, KC exhibits a maximum Tc of 21.4 K at 25 GPa, which is primarily attributed to the robust coupling between low-frequency K- and C-derived phonon modes and C 2p electrons at the Fermi level. In addition, KC3 is calculated to have a Tc value of 6.7 K at 25 GPa. This study provides valuable insights into K-C compounds and broadens the diversity of metal carbide superconductors. |
| title | Electride States and Superconductivity in Dense Potassium Carbides |
| topic | Superconductivity |
| url | https://arxiv.org/abs/2605.27201 |