{
  "abstract": "The luminescence of doped nanocrystals is usually optimised through the activator; here we show that the host cation ratio is an equally decisive, and largely overlooked, design variable. Mn-doped ZnGa$_2$O$_4$ nanocrystals (Mn:Zn = $4\\times10^{-4}$) were grown hydrothermally at nominal Zn/Ga ratios between 0.30 and 0.75 (stoichiometric: 0.50) and post-annealed at 400--1100$^\\circ$C, and the resulting composition--temperature matrix was mapped by X-ray- and UV-excited luminescence, EPR, Rietveld-refined X-ray diffraction, Raman spectroscopy and SEM. The as-grown crystals are phase-pure spinel at every composition and accommodate their off-stoichiometry internally as a point-defect inventory, reflected in a 0.4\\% variation of the lattice parameter; on annealing, the excess gallium is exsolved as $β$-Ga$_2$O$_3$ in amounts set by the solution composition. The Mn$^{2+}$ emission separates into two optima, near-stoichiometric crystals annealed at 400--600$^\\circ$C and Zn-excess crystals annealed at 1100$^\\circ$C, the latter being twice as bright under X-ray excitation. Under X-ray and 365~nm excitation the two optima are separated by a minimum at 800$^\\circ$C that coincides with a collapse of the Mn$^{2+}$ EPR population and has no counterpart in the Raman linewidths, identifying transient, defect-compensated oxidation of the dopant rather than lattice degradation as its origin. The most Zn-rich composition shows neither Mn$^{2+}$ nor Mn$^{4+}$ emission at any annealing stage, whereas its trace Cr$^{3+}$ emission is strong, indicating that Mn is rejected already during growth. Solution stoichiometry therefore acts on two levels, dopant capture and native-defect inventory, while annealing controls dopant valence and lattice order. The brightest high-temperature phosphor is thus not the nominally stoichiometric one, but the composition whose excess is consumed on its way to stoichiometry.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2610.14195",
  "author_total": 8,
  "authors": [
    {
      "name": "Mátyás M. Rudolf"
    },
    {
      "name": "Gábor Bortel"
    },
    {
      "name": "Nikoletta Jegenyés"
    },
    {
      "name": "Árpád Jakab"
    },
    {
      "name": "László Bencs"
    },
    {
      "name": "Ferenc Simon"
    },
    {
      "name": "Adam Gali"
    },
    {
      "name": "Dávid Beke"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/e0a4qban0jz2r.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2610.14195",
  "fulltext_url": null,
  "id": "e0a4qban0jz2r",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2610.14195",
  "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"
    ],
    [
      "arxiv",
      "physics.optics"
    ],
    [
      "openalex",
      "2505|Luminescence Properties of Advanced Materials"
    ]
  ],
  "openalex": "W7221800838",
  "pdf_url": "https://arxiv.org/pdf/2610.14195",
  "pmcid": null,
  "pmid": null,
  "published": "2026-10-09",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/e0a4qban0jz2r.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:29:06Z",
      "native_id": "2610.14195",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2610.14195"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "arxiv:physics.chem-ph",
      "subfield": "physical"
    },
    {
      "field": "physics",
      "origin": "arxiv:cond-mat.mtrl-sci",
      "subfield": "condensed-matter"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.optics",
      "subfield": "optics-photonics"
    }
  ],
  "title": "Precursor stoichiometry controls dopant structure, defect chemistry, and valence in Mn-doped ZnGa$_2$O$_4$ nanocrystals",
  "title_text": "Precursor stoichiometry controls dopant structure, defect chemistry, and valence in Mn-doped ZnGa_2O_4 nanocrystals",
  "type": "preprint",
  "updated_at": "2026-10-30T12:29:06Z",
  "url": "https://research.draconitic.com/paper/e0a4qban0jz2r",
  "venue": "arXiv",
  "versions": []
}