{
  "abstract": "Earth's lower mantle hosts large low shear-velocity provinces (LLSVPs) beneath Africa and the Pacific, but their origin remains debated. Davemaoite, a major lower-mantle mineral, has been proposed as a contributor to these anomalies; however, its experimentally measured shear modulus is approximately 30% lower than first-principles predictions, a longstanding discrepancy between theory and experiment. Here, using million-atom machine-learning molecular dynamics simulations, we show that nanoscale grain-boundary disorder, invisible to conventional x-ray diffraction, can reconcile this gap. Introducing 5.8 vol% disordered regions reduces the shear and bulk moduli by 37% and 12%, respectively. This shear-selective softening can reproduce LLSVP-like seismic anomalies in basalt-rich assemblages, but only at disorder levels corresponding to grain sizes smaller than those expected in the lower mantle. Combining the disorder-elasticity relationship with seismic constraints, we derive a minimum davemaoite grain size of approximately 100 nm. This limit is consistent with mantle grain growth models and with attenuation-based evidence for coarse-grained LLSVPs.",
  "abstract_shown": true,
  "affiliations": [],
  "article_type": null,
  "arxiv": "2609.39423",
  "author_total": 6,
  "authors": [
    {
      "name": "Peiyu Zhang"
    },
    {
      "name": "Liang Yuan"
    },
    {
      "name": "Rong Huang"
    },
    {
      "name": "Yu Ye"
    },
    {
      "name": "Xiang Wu"
    },
    {
      "name": "Junfeng Zhang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/62z38j2rbdfh6.bib",
  "cited_by": 0,
  "doi": "10.48550/arxiv.2609.39423",
  "fulltext_url": null,
  "id": "62z38j2rbdfh6",
  "issns": [],
  "landing_url": "https://arxiv.org/abs/2609.39423",
  "language": null,
  "licence": "LicenseRef-arXiv-nonexclusive-1.0",
  "licence_label": "arXiv licence",
  "licence_source": "article",
  "licence_url": "http://arxiv.org/licenses/nonexclusive-distrib/1.0/",
  "metadata_licence": "CC0-1.0",
  "native_subjects": [
    [
      "arxiv",
      "physics.chem-ph"
    ],
    [
      "arxiv",
      "physics.comp-ph"
    ],
    [
      "arxiv",
      "physics.geo-ph"
    ],
    [
      "openalex",
      "1908|High-pressure geophysics and materials"
    ]
  ],
  "openalex": "W7215071454",
  "pdf_url": "https://arxiv.org/pdf/2609.39423",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-30",
  "publisher": null,
  "ris": "https://research.draconitic.com/paper/62z38j2rbdfh6.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:25:49Z",
      "native_id": "2609.39423",
      "source": "arxiv",
      "url": "https://arxiv.org/abs/2609.39423"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "arxiv:physics.chem-ph",
      "subfield": "physical"
    },
    {
      "field": "earth",
      "origin": "arxiv:physics.geo-ph",
      "subfield": "geophysics"
    },
    {
      "field": "physics",
      "origin": "arxiv:physics.comp-ph",
      "subfield": "computational"
    }
  ],
  "title": "Elasticity of polycrystalline davemaoite constrains its grain size in the lower mantle",
  "title_text": "Elasticity of polycrystalline davemaoite constrains its grain size in the lower mantle",
  "type": "preprint",
  "updated_at": "2026-10-30T12:25:49Z",
  "url": "https://research.draconitic.com/paper/62z38j2rbdfh6",
  "venue": "arXiv",
  "versions": []
}