Absence of higher than 6-fold coordination in glassy $GeO_{2}$ up to 158 GPa revealed by X-ray absorption spectroscopy
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| Autores principales: | , , , , , , , |
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| Formato: | Preprint |
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2025
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| _version_ | 1866909676895993856 |
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| author | Rodrigues, João Elias F. S. Rosa, Angelika D. Mijit, Emin Irifune, Tetsuo Garbarino, Gaston Mathon, Olivier Torchio, Raffaella Wilke, Max |
| author_facet | Rodrigues, João Elias F. S. Rosa, Angelika D. Mijit, Emin Irifune, Tetsuo Garbarino, Gaston Mathon, Olivier Torchio, Raffaella Wilke, Max |
| contents | Simple binary oxide glasses can exhibit a compression behavior distinct from that of their crystalline counterparts. In this study, we employed high-pressure X-ray absorption spectroscopy coupled to the diamond anvil cell to investigate in detail local structural changes around Ge in glassy $GeO_{2}$ up to 158 GPa. We conducted four independent runs, both with and without pressure-transmitting media. Up to 30 GPa, we observed no significant influence of the pressure medium on the pressure dependence of the $Ge-O$ bond length ($<R_{Ge-O}>$). Between 10 and 30 GPa, the evolution of $<R_{Ge-O}>$ shows substantial variability across our experiments and previous works. The measured values lie close to those reported for crystalline polymorphs, including the rutile- and $CaCl_{2}$-type phase of $GeO_{2}$. This finding suggests that the amorphous structure possesses considerable flexibility to transition among different atomic configurations. From 30 GPa to 158 GPa, our results for both $<R_{Ge-O}>$ and the non-bonded cation-cation distance $<R_{Ge...Ge}>$ demonstrate that edge-sharing octahedra remain the main structural motives in glassy $GeO_{2}$. Up to 100 GPa, compaction proceeds primarily via distortions of octahedral $O-Ge-O$ bond angles accompanied by octahedral bond shortening. Above 100 GPa, octahedral distortion becomes the prevailing mechanism. Compared to its crystalline analogues ($α-PbO_{2}$ and pyrite-like phase), glassy $GeO_{2}$ exhibits a slightly less efficient compaction mechanism, likely due to kinetic constraints that inhibit reconstructive lattice rearrangements. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2507_04076 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Absence of higher than 6-fold coordination in glassy $GeO_{2}$ up to 158 GPa revealed by X-ray absorption spectroscopy Rodrigues, João Elias F. S. Rosa, Angelika D. Mijit, Emin Irifune, Tetsuo Garbarino, Gaston Mathon, Olivier Torchio, Raffaella Wilke, Max Materials Science Disordered Systems and Neural Networks Simple binary oxide glasses can exhibit a compression behavior distinct from that of their crystalline counterparts. In this study, we employed high-pressure X-ray absorption spectroscopy coupled to the diamond anvil cell to investigate in detail local structural changes around Ge in glassy $GeO_{2}$ up to 158 GPa. We conducted four independent runs, both with and without pressure-transmitting media. Up to 30 GPa, we observed no significant influence of the pressure medium on the pressure dependence of the $Ge-O$ bond length ($<R_{Ge-O}>$). Between 10 and 30 GPa, the evolution of $<R_{Ge-O}>$ shows substantial variability across our experiments and previous works. The measured values lie close to those reported for crystalline polymorphs, including the rutile- and $CaCl_{2}$-type phase of $GeO_{2}$. This finding suggests that the amorphous structure possesses considerable flexibility to transition among different atomic configurations. From 30 GPa to 158 GPa, our results for both $<R_{Ge-O}>$ and the non-bonded cation-cation distance $<R_{Ge...Ge}>$ demonstrate that edge-sharing octahedra remain the main structural motives in glassy $GeO_{2}$. Up to 100 GPa, compaction proceeds primarily via distortions of octahedral $O-Ge-O$ bond angles accompanied by octahedral bond shortening. Above 100 GPa, octahedral distortion becomes the prevailing mechanism. Compared to its crystalline analogues ($α-PbO_{2}$ and pyrite-like phase), glassy $GeO_{2}$ exhibits a slightly less efficient compaction mechanism, likely due to kinetic constraints that inhibit reconstructive lattice rearrangements. |
| title | Absence of higher than 6-fold coordination in glassy $GeO_{2}$ up to 158 GPa revealed by X-ray absorption spectroscopy |
| topic | Materials Science Disordered Systems and Neural Networks |
| url | https://arxiv.org/abs/2507.04076 |