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| Main Authors: | , , , , |
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| Format: | Preprint |
| Published: |
2026
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| Subjects: | |
| Online Access: | https://arxiv.org/abs/2604.08901 |
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| _version_ | 1866915929743425536 |
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| author | Ma, Shuran Cong, Xue Wang, Yanchang Chen, Yuanzheng Liu, Zhen |
| author_facet | Ma, Shuran Cong, Xue Wang, Yanchang Chen, Yuanzheng Liu, Zhen |
| contents | While the high oxidation states in heavy alkali fluorides (Cs, Ba, Ra) have been attributed to a pressure-driven upshift of energy level of inner p states, this route is largely ineffective for Rb because its smaller ionic radius suppresses the required level rise even under strong compression. Here, we predict a high-pressure layered ternary phase, RbBF5, in which 12-fold truncated-cube-like F coordination around Rb breaks local symmetry and activates the Rb 4p inner shell. The resulting orbital splitting selectively elevates the in-plane Rb 4px,y levels toward the F 2p manifold, enabling inner-shell participation and stabilizing Rb-F bonding under compression. More broadly, this symmetry-lowering coordination motif may provide a general mechanism for activating inner-shell p states in other alkali metals (e.g., K and Cs inner p states). These findings extend inner-shell chemistry to lighter main-group elements and establish a design principle for accessing unconventional bonding and oxidation states at high pressure. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2604_08901 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Activation of Inner-Shell 4p-Orbital Electrons of Rubidium Driven by Asymmetric Coordination at High Pressure Ma, Shuran Cong, Xue Wang, Yanchang Chen, Yuanzheng Liu, Zhen Materials Science While the high oxidation states in heavy alkali fluorides (Cs, Ba, Ra) have been attributed to a pressure-driven upshift of energy level of inner p states, this route is largely ineffective for Rb because its smaller ionic radius suppresses the required level rise even under strong compression. Here, we predict a high-pressure layered ternary phase, RbBF5, in which 12-fold truncated-cube-like F coordination around Rb breaks local symmetry and activates the Rb 4p inner shell. The resulting orbital splitting selectively elevates the in-plane Rb 4px,y levels toward the F 2p manifold, enabling inner-shell participation and stabilizing Rb-F bonding under compression. More broadly, this symmetry-lowering coordination motif may provide a general mechanism for activating inner-shell p states in other alkali metals (e.g., K and Cs inner p states). These findings extend inner-shell chemistry to lighter main-group elements and establish a design principle for accessing unconventional bonding and oxidation states at high pressure. |
| title | Activation of Inner-Shell 4p-Orbital Electrons of Rubidium Driven by Asymmetric Coordination at High Pressure |
| topic | Materials Science |
| url | https://arxiv.org/abs/2604.08901 |