Micro-environment of the Eu interstitial in $β$-SiAlON:Eu$^{2+}$ green phosphor
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arXiv
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| Format: | Preprint |
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2026
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| author | Bouquiaux, Julien Poncé, Samuel Jia, Yongchao Mikami, Masayoshi Gonze, Xavier |
| author_facet | Bouquiaux, Julien Poncé, Samuel Jia, Yongchao Mikami, Masayoshi Gonze, Xavier |
| contents | The precise atomic-scale structure around Eu$^{2+}$ activators in the $β$-Si$_{6-z}$Al$_z$O$_z$N$_{8-z}$:Eu$^{2+}$ commercial green phosphor remains elusive. We use the first-principles $Δ$SCF excited-state method, embedding of the interatomic force constants for supercells up to 3501 atoms, and Huang-Rhys theory to clarify this issue. Monte Carlo exploration is used to identify representative low-energy structural models spanning different levels of Al/O concentration $z$. For the lowest-energy structure at low $z$, our computed photoluminescence spectrum reproduces the experimental vibronic peaks at 6~K with excellent agreement in peak positions and intensities, validating the Eu-N$_9$ coordination model with Al, O, and Eu confined to the same crystallographic plane. Analysis of the low-energy structures reveals that the electron-phonon coupling is weak ($S \approx 2.15$) with a robust characteristic phonon signature across different Al/O arrangements, explaining the surprising persistence of resolved phonon replicas with increasing $z$. We explain the experimentally observed red-shift of emission with increasing $z$ through systematic trends in zero-phonon line energies, modest increases in Huang-Rhys factors, and larger configurational diversity at higher compositions. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2605_10665 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Micro-environment of the Eu interstitial in $β$-SiAlON:Eu$^{2+}$ green phosphor Bouquiaux, Julien Poncé, Samuel Jia, Yongchao Mikami, Masayoshi Gonze, Xavier Materials Science The precise atomic-scale structure around Eu$^{2+}$ activators in the $β$-Si$_{6-z}$Al$_z$O$_z$N$_{8-z}$:Eu$^{2+}$ commercial green phosphor remains elusive. We use the first-principles $Δ$SCF excited-state method, embedding of the interatomic force constants for supercells up to 3501 atoms, and Huang-Rhys theory to clarify this issue. Monte Carlo exploration is used to identify representative low-energy structural models spanning different levels of Al/O concentration $z$. For the lowest-energy structure at low $z$, our computed photoluminescence spectrum reproduces the experimental vibronic peaks at 6~K with excellent agreement in peak positions and intensities, validating the Eu-N$_9$ coordination model with Al, O, and Eu confined to the same crystallographic plane. Analysis of the low-energy structures reveals that the electron-phonon coupling is weak ($S \approx 2.15$) with a robust characteristic phonon signature across different Al/O arrangements, explaining the surprising persistence of resolved phonon replicas with increasing $z$. We explain the experimentally observed red-shift of emission with increasing $z$ through systematic trends in zero-phonon line energies, modest increases in Huang-Rhys factors, and larger configurational diversity at higher compositions. |
| title | Micro-environment of the Eu interstitial in $β$-SiAlON:Eu$^{2+}$ green phosphor |
| topic | Materials Science |
| url | https://arxiv.org/abs/2605.10665 |