Input:
Single crystalline PbSe was prepared in a two-step process using Pb and Se materials with 99.999% metals-based purity. First, polycrystalline PbSe was obtained by reacting Pb and Se in a quartz ampoule at 1100 °C. The resulting material was crushed and placed into a quartz ampoule with a tapered bottom, which had been prepared by washing with nitric acid, rinsing with deionized water, and drying. A large single crystal (>10 g) was grown using the gradient freeze method. During this crystal growth, the quartz ampoule was supported by a quartz rod, which resulted in a cold finger effect that caused a crystal to be grown at the top of the ampoule due to vapor transport.

Output:
[
  {
    "label": "PbSe",
    "@graph": [
      {
        "@type": "Entity",
        "@id": "e1",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "Pb" }],
        "matprov:purity": [{ "@value": "99.999%" }]
      },
      {
        "@type": "Entity",
        "@id": "e2",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "Se" }],
        "matprov:purity": [{ "@value": "99.999%" }]
      },
      {
        "@type": "Entity",
        "@id": "e3",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "reacted sample" }],
        "matprov:form": [{ "@value": "polycrystalline" }]
      },
      {
        "@type": "Entity",
        "@id": "e4",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "crushed sample" }]
      },
      {
        "@type": "Entity",
        "@id": "e5",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "placed sample" }]
      },
      {
        "@type": "Entity",
        "@id": "e6",
        "type": [{ "@value": "material" }],
        "label": [{ "@value": "gradient frozen sample" }],
        "matprov:form": [{ "@value": "single crystal" }]
      },
      {
        "@type": "Entity",
        "@id": "e7",
        "type": [{ "@value": "tool" }],
        "label": [{ "@value": "quartz ampoule" }]
      },
      {
        "@type": "Entity",
        "@id": "e8",
        "type": [{ "@value": "tool" }],
        "label": [{ "@value": "quartz ampoule with a tapered bottom" }]
      },
      {
        "@type": "Entity",
        "@id": "e9",
        "type": [{ "@value": "tool" }],
        "label": [{ "@value": "quartz rod" }]
      },
      {
        "@type": "Activity",
        "@id": "a1",
        "label": [{ "@value": "reacting" }],
        "matprov:temperature": [{ "@value": "1100 °C" }]
      },
      {
        "@type": "Activity",
        "@id": "a2",
        "label": [{ "@value": "crushing" }]
      },
      {
        "@type": "Activity",
        "@id": "a3",
        "label": [{ "@value": "placing" }]
      },
      {
        "@type": "Activity",
        "@id": "a4",
        "label": [{ "@value": "gradient freezing" }]
      },
      { "@type": "Usage", "activity": "a1", "entity": "e1" },
      { "@type": "Usage", "activity": "a1", "entity": "e2" },
      { "@type": "Usage", "activity": "a1", "entity": "e7" },
      { "@type": "Generation", "activity": "a1", "entity": "e3" },
      { "@type": "Usage", "activity": "a2", "entity": "e3" },
      { "@type": "Generation", "activity": "a2", "entity": "e4" },
      { "@type": "Usage", "activity": "a3", "entity": "e4" },
      { "@type": "Usage", "activity": "a3", "entity": "e8" },
      { "@type": "Generation", "activity": "a3", "entity": "e5" },
      { "@type": "Usage", "activity": "a4", "entity": "e5" },
      { "@type": "Usage", "activity": "a4", "entity": "e9" },
      { "@type": "Generation", "activity": "a4", "entity": "e6" }
    ]
  }
]