{
  "abstract": "Efficient and durable phosphors made from abundant elements underpin energy-saving solid-state lighting, near-infrared light sources for sensing, and X-ray and biomedical imaging. Co-doping is a standard route to brighter phosphors, yet the fate of the co-dopants is rarely established. We combine quantitative electron paramagnetic resonance (EPR) spin counting with photoluminescence, photoluminescence excitation, and X-ray-excited spectroscopy across two dilute Mn/Cr co-doping series of hydrothermally grown $\\mathrm{ZnAl_2O_4}$ nanoparticles and show that the two ions can form an exchange-coupled, edge-sharing Cr--Mn defect complex, with $\\mathrm{Mn^{2+/4+}}$ entering an octahedral site next to $\\mathrm{Cr^{3+}}$. The octahedral Mn lifts the inversion symmetry of the $\\mathrm{Cr^{3+}}$ site and strengthens its parity-forbidden absorption, enhancing the $\\mathrm{Cr^{3+}}$ emission without energy transfer. The population of the defect complex follows the law of mass action, and above a threshold Mn concentration, Mn re-partitions into EPR-silent octahedral configurations that quench both emissions. Concentration optima in co-doped phosphors can thus reflect defect speciation, not only energy-transfer efficiency, which opens a structural design handle for brighter emitters.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.14262",
  "author_total": 8,
  "authors": [
    {
      "name": "Apoko S. Omondi"
    },
    {
      "name": "Mátyás M. Rudolf"
    },
    {
      "name": "Nikoletta Jegenyés"
    },
    {
      "name": "Árpád Jakab"
    },
    {
      "name": "Gábor Bortel"
    },
    {
      "name": "Bence G. Márkus"
    },
    {
      "name": "Adam Gali"
    },
    {
      "name": "Dávid Beke"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/fs27pttdar1x9.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.14262",
  "fulltext_url": null,
  "id": "fs27pttdar1x9",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.14262",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "http://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "cond-mat.mtrl-sci"
    ],
    [
      "arxiv",
      "physics.chem-ph"
    ],
    [
      "openalex",
      "2505|Luminescence Properties of Advanced Materials"
    ]
  ],
  "openalex": "W7221793697",
  "pdf_url": "https://arxiv.org/pdf/2610.14262",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/fs27pttdar1x9.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:06Z",
      "native_id": "2610.14262",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.14262"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "arxiv:physics.chem-ph",
      "subfield": "physical"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    }
  ],
  "title": "Mn--Cr dopant association in dilute co-doped $\\mathrm{ZnAl_2O_4}$ revealed by combined EPR and optical spectroscopy",
  "title_text": "Mn--Cr dopant association in dilute co-doped ZnAl_2O_4 revealed by combined EPR and optical spectroscopy",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:06Z",
  "url": "https://research.draconitic.com/paper/fs27pttdar1x9",
  "venue": "arXiv",
  "versions": []
}