{
  "spore": "profile",
  "id": "cvd-diamond",
  "spore_version": "0.2",
  "family": "diamond",
  "name": "CVD diamond (polycrystalline and single-crystal)",
  "abbreviation": "CVD diamond",
  "role": "heat spreader, optical window",
  "category": "carbon",
  "type": "diamond",
  "summary": "CVD diamond is carbon grown from hydrocarbon gas by chemical vapour deposition, as polycrystalline plates or as single crystals. Element Six prints a thermal conductivity of greater than 2200 W m-1 K-1 at 300 K for its polycrystalline optical grade and for its single-crystal optical grade. The same brochure prints a density of 3.52 x 10³ kg m⁻³ and a coefficient of thermal expansion of 1.0 ppm/K at 300 K.\n",
  "best_for": "Heat spreaders and high-power laser windows, where thermal conductivity above 2000 W/(m·K) at 300 K matters most",
  "weakest_at": "Size and thickness: polycrystalline optical windows up to Ø 135 mm and 3 mm thick, single-crystal plates up to 7 x 7 x 2 mm (Element Six)",
  "identity": {
    "formula": "C, carbon in the diamond cubic structure (eight atoms per unit cell, Wikipedia)",
    "crystal_system": "cubic",
    "designations": [],
    "source": "wikipedia-diamond",
    "where": "Crystal structure section: diamond cubic, unit cell side 3.567 angstroms, eight atoms per unit cell"
  },
  "tags": {
    "environments": [],
    "stresses": [
      "dust-abrasion"
    ],
    "applications": [
      "thermal-control",
      "optics-and-cameras",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, polycrystalline CVD diamond, optical grade, 300 K",
      "value": 2200,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "temperature": "300 K",
        "unit_in_source": "W m-1 K-1, printed as >2200"
      },
      "method": "Lower limit printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal conductivity 300 K, column Polycrystalline Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, polycrystalline CVD diamond, RF grade, 300 K",
      "value": 2000,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, RF grade",
        "temperature": "300 K",
        "unit_in_source": "W m-1 K-1, printed as >2000"
      },
      "method": "Lower limit printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal conductivity 300 K, column RF grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, single-crystal CVD diamond, optical grade, 300 K",
      "value": 2200,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade",
        "temperature": "300 K",
        "unit_in_source": "W m-1 K-1, printed as >2200"
      },
      "method": "Lower limit printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal conductivity 300 K, column Single crystal Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, polycrystalline CVD diamond, optical grade, 425 K",
      "value": 1600,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "temperature": "425 K",
        "unit_in_source": "W m-1 K-1, printed as >1600"
      },
      "method": "Lower limit printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal conductivity 425 K, column Polycrystalline Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, single-crystal CVD diamond sheet (SCD-O), temperature not stated",
      "value": 2200,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade (SCD-O), table labels it Thermal Grade",
        "temperature": "not stated on the datasheet",
        "unit_in_source": "W/mK, printed as ≥2,200"
      },
      "method": "Lower limit printed in a manufacturer datasheet; no temperature given",
      "status": "ground",
      "note": "Matches the Element Six single-crystal optical grade value at 300 K, but the datasheet does not print the temperature.",
      "source": "coherent-scd-o",
      "where": "Material Properties table, row Thermal Conductivity",
      "source_detail": {
        "title": "Coherent, Single Crystal Diamond, Optical Grade (SCD-O) datasheet",
        "url": "https://www.coherent.com/content/dam/coherent/site/en/resources/datasheet/optics/single-crystal-diamond-optical-grade.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Element Six Diafilm TM100, 300 K",
      "value": 1000,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Element Six Diafilm TM100, polycrystalline CVD heat spreader",
        "temperature": "300 K",
        "unit_in_source": "W/m-K, printed as better than 1,000"
      },
      "method": "Lower limit printed in a trade article that reports Element Six product data",
      "status": "ground",
      "source": "mwrf-diafilm",
      "where": "Thermal conductivity table, row Diafilm TM100, column At 300 K",
      "source_detail": {
        "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
        "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
        "year": 2017,
        "kind": "web",
        "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_conductivity",
      "label": "Thermal conductivity, Element Six Diafilm TM200, 300 K",
      "value": 2000,
      "bound": "lower",
      "unit": "W/(m·K)",
      "scope": "material",
      "conditions": {
        "grade": "Element Six Diafilm TM200, polycrystalline CVD heat spreader",
        "temperature": "300 K",
        "unit_in_source": "W/m-K, printed as better than 2,000"
      },
      "method": "Lower limit printed in a trade article that reports Element Six product data",
      "status": "ground",
      "source": "mwrf-diafilm",
      "where": "Thermal conductivity table, row Diafilm TM200, column At 300 K",
      "source_detail": {
        "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
        "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
        "year": 2017,
        "kind": "web",
        "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, CVD diamond, 300 K",
      "value": 1,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "temperature": "300 K",
        "unit_in_source": "ppm K-1"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "note": "The Diafilm article prints 1.0 ± 0.1 ppm/K at 300 K for four Diafilm grades, which agrees.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal expansion coefficient 300 K",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "cte",
      "label": "Coefficient of thermal expansion, CVD diamond, 1000 K",
      "value": 4.4,
      "bound": "exact",
      "unit": "ppm/K",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "temperature": "1000 K",
        "unit_in_source": "ppm K-1"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Thermal expansion coefficient 1000 K",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density, CVD diamond",
      "value": 3.52,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "unit_in_source": "3.52 x 10³ kg m⁻³ (printed in the table heading, which equals 3.52 g/cm3)"
      },
      "method": "Value printed as 3.52 in a manufacturer properties table under the heading x 10³ kg m⁻³; the same figure is entered in g/cm3 (1 g/cm3 = 1000 kg/m3). The Diafilm article prints 3.52 x 10³ kg/m³ for its four grades.",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Density",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, CVD diamond, 500 K",
      "value": 520,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "temperature": "500 K",
        "unit_in_source": "J Kg-1 K-1"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Specific heat capacity at 500 K",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, Diafilm grades, 300 K",
      "value": 520,
      "bound": "exact",
      "unit": "J/(kg·K)",
      "scope": "material",
      "conditions": {
        "grade": "Element Six Diafilm TM grades (printed for all four)",
        "temperature": "300 K",
        "unit_in_source": "J/kg/K"
      },
      "method": "Value printed in a trade article that reports Element Six product data",
      "status": "ground",
      "source": "mwrf-diafilm",
      "where": "Other properties list, Specific heat capacity",
      "source_detail": {
        "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
        "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
        "year": 2017,
        "kind": "web",
        "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
      }
    },
    {
      "benchmark": "specific_heat",
      "label": "Specific heat capacity, single-crystal CVD diamond sheet (SCD-O), 25 °C",
      "value": 0.536,
      "bound": "exact",
      "unit": "J/g-K",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade (SCD-O)",
        "temperature": "25 °C",
        "unit_in_source": "J/g-K"
      },
      "method": "Value printed in a manufacturer datasheet",
      "status": "ground",
      "note": "Differs in unit form and temperature from the 520 J/(kg·K) values; 0.536 J/g-K is 536 J/(kg·K). Both are kept, with their temperatures.",
      "source": "coherent-scd-o",
      "where": "Material Properties table, row Specific Heat (25 °C)",
      "source_detail": {
        "title": "Coherent, Single Crystal Diamond, Optical Grade (SCD-O) datasheet",
        "url": "https://www.coherent.com/content/dam/coherent/site/en/resources/datasheet/optics/single-crystal-diamond-optical-grade.pdf",
        "year": 2026,
        "kind": "datasheet",
        "license": "Manufacturer datasheet, cited, not reproduced"
      }
    },
    {
      "benchmark": "elastic_modulus",
      "label": "Young's modulus, Element Six Diafilm grades",
      "value": 1000,
      "value_high": 1100,
      "bound": "range",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "Element Six Diafilm TM grades (same printed range for all four)",
        "temperature": "not stated",
        "unit_in_source": "GPa, printed as 1,000 to 1,100"
      },
      "method": "Range printed in a trade article that reports Element Six product data",
      "status": "ground",
      "note": "The Element Six brochure prints 1050 in the Young's modulus row with no unit, so that value is not entered.",
      "source": "mwrf-diafilm",
      "where": "Other properties list, Young's modulus",
      "source_detail": {
        "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
        "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
        "year": 2017,
        "kind": "web",
        "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
      }
    },
    {
      "benchmark": "hardness",
      "label": "Hardness, polycrystalline CVD diamond",
      "value": 81,
      "bound": "exact",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond (value spans the two polycrystalline columns)",
        "unit_in_source": "GPa, printed as 81 ± 18"
      },
      "method": "Value printed in a manufacturer properties table, with a stated spread of ± 18 GPa",
      "status": "ground",
      "note": "The spread of ± 18 GPa is printed beside the mean; the brochure does not say whether it is a standard deviation.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Hardness (GPa)",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "hardness",
      "label": "Hardness, single-crystal CVD diamond",
      "value": 70,
      "value_high": 120,
      "bound": "range",
      "unit": "GPa",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond (value spans the two single-crystal columns)",
        "unit_in_source": "GPa, printed as 70 - 120"
      },
      "method": "Range printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Hardness (GPa)",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, CVD diamond at 10.6 µm",
      "value": 2.376,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "wavelength": "10.6 µm"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Refractive index 10.6 µm",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, CVD diamond at 1550 nm",
      "value": 2.386,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "wavelength": "1550 nm"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Refractive index 1550 nm",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index, CVD diamond at 1064 nm",
      "value": 2.392,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "wavelength": "1064 nm"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "note": "The chart on page 3 of the same brochure reads 2.390 at 1064 nm, so the two values differ by 0.002. The table value is entered.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Refractive index 1064 nm; chart on page 3 for comparison",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "refractive_index_temperature_coefficient",
      "label": "Temperature coefficient of refractive index (dn/dT), CVD diamond",
      "value": 0.0000096,
      "bound": "exact",
      "unit": "K-1",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "unit_in_source": "9.6 x 10-6 (K-1)"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row dn/dT",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "birefringence",
      "label": "Birefringence, single-crystal CVD diamond, optical plus grade",
      "value": 0.00005,
      "bound": "upper",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical plus",
        "unit_in_source": "<5 x 10-5 (Δn, dimensionless)"
      },
      "method": "Upper limit printed in a manufacturer properties table",
      "status": "ground",
      "note": "The Coherent SCD-O datasheet prints the same limit, <5 x 10-5 Δn, for its single-crystal optical grade.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Birefringence, column Optical plus",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "birefringence",
      "label": "Birefringence, single-crystal CVD diamond, optical grade",
      "value": 0.0001,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade",
        "unit_in_source": "1 x 10-4 (Δn, dimensionless)"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "note": "The Element Six table gives 1 x 10-4 for this grade, while the Coherent SCD-O datasheet gives less than 5 x 10-5 for its optical grade. Both are kept side by side and the grades may differ.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Birefringence, column Single crystal Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "absorption_coefficient",
      "label": "Absorption coefficient at 10.6 µm, polycrystalline CVD diamond, optical grade",
      "value": 0.07,
      "bound": "upper",
      "unit": "cm-1",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "wavelength": "10.6 µm",
        "unit_in_source": "<0.07 cm-1"
      },
      "method": "Upper limit printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Absorption coefficient 10.6 µm, column Polycrystalline Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "absorption_coefficient",
      "label": "Absorption coefficient at 10.6 µm, single-crystal CVD diamond, optical grade",
      "value": 0.05,
      "bound": "upper",
      "unit": "cm-1",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade",
        "wavelength": "10.6 µm",
        "unit_in_source": "<0.05 cm-1"
      },
      "method": "Upper limit printed in a manufacturer properties table",
      "status": "ground",
      "note": "The Coherent SCD-O datasheet prints the same limit, 10.6 µm ABS coefficient <0.05 (cm-1).",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Absorption coefficient 10.6 µm, column Single crystal Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "absorption_coefficient",
      "label": "Absorption coefficient at 1064 nm, single-crystal CVD diamond, optical plus grade",
      "value": 0.005,
      "bound": "upper",
      "unit": "cm-1",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical plus",
        "wavelength": "1064 nm",
        "unit_in_source": "<0.005"
      },
      "method": "Upper limit printed in a manufacturer properties table",
      "status": "ground",
      "note": "The Coherent SCD-O datasheet prints 0.005 (cm-1) at 1.064 µm for its single-crystal optical grade, which agrees.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Absorption coefficient 1064 nm, column Single crystal Optical plus",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "transmittance",
      "label": "Transmittance at 1 mm thickness, polycrystalline CVD diamond, optical grade, 8 to 200 µm",
      "value": 71.4,
      "bound": "exact",
      "unit": "%",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "thickness": "1 mm",
        "wavelength": "8 to 200 µm"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Transmittance 8-200 µm, column Polycrystalline Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, polycrystalline CVD diamond, 35 GHz",
      "value": 5.68,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond (value spans the two polycrystalline columns)",
        "frequency": "35 GHz"
      },
      "method": "Value printed in a manufacturer properties table, with a stated spread of ± 0.15",
      "status": "ground",
      "note": "The spread of ± 0.15 is printed beside the value. The brochure gives 4.3 % increase in D at 773 K and does not give the value at that temperature.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Dielectric constant D (35 GHz)",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "dissipation_factor",
      "label": "Loss tangent at 145 GHz, polycrystalline CVD diamond, optical grade",
      "value": 0.000008,
      "value_high": 0.00002,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "frequency": "145 GHz",
        "unit_in_source": "8 - 20 (x 10-6)"
      },
      "method": "Range printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Loss tangent 145 GHz, column Optical grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "dissipation_factor",
      "label": "Loss tangent at 145 GHz, polycrystalline CVD diamond, RF grade",
      "value": 0.00001,
      "value_high": 0.0001,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, RF grade",
        "frequency": "145 GHz",
        "unit_in_source": "10 - 100 (x 10-6)"
      },
      "method": "Range printed in a manufacturer properties table",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Loss tangent 145 GHz, column RF grade",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "fracture_stress",
      "label": "Fracture stress, single-crystal CVD diamond, optical grade and optical plus",
      "value": 3500,
      "bound": "exact",
      "unit": "MPa",
      "scope": "material",
      "conditions": {
        "grade": "single-crystal CVD diamond, optical grade and optical plus (same value printed for both)",
        "weibull_modulus": "2.5",
        "unit_in_source": "MPa, Weibull modulus printed in brackets"
      },
      "method": "Value printed in a manufacturer properties table with its Weibull modulus",
      "status": "ground",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Fracture stress (MPa) [Weibull modulus]",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "sand_erosion",
      "label": "Sand erosion, polycrystalline CVD diamond, optical grade",
      "value": 2.1,
      "bound": "exact",
      "unit": "mg/kg",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "sand": "C300/600",
        "velocity": "100 m/s",
        "unit_in_source": "mg kg-1 at 100 ms-1 C300/600 sand"
      },
      "method": "Value printed in a manufacturer properties table, with a stated spread of ± 0.6",
      "status": "ground",
      "note": "The brochure gives no single-crystal value for sand erosion.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Sand erosion",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "emittance",
      "label": "Emittance at 10 µm, CVD diamond, 573 K",
      "value": 0.02,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "grade": "polycrystalline and single-crystal CVD diamond (same value printed for both)",
        "wavelength": "10 µm",
        "temperature": "573 K"
      },
      "method": "Value printed in a manufacturer properties table",
      "status": "ground",
      "note": "At 773 K the same table prints 0.03.",
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Emittance at 10 µm, 573 K",
      "source_detail": {
        "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
        "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
        "year": 2021,
        "kind": "datasheet",
        "license": "Manufacturer brochure, cited, not reproduced"
      }
    },
    {
      "benchmark": "thermal_diffusivity",
      "label": "Thermal diffusivity, Element Six Diafilm TM200, 300 K",
      "value": 11.1,
      "bound": "lower",
      "unit": "cm2/s",
      "scope": "material",
      "conditions": {
        "grade": "Element Six Diafilm TM200, polycrystalline CVD heat spreader",
        "temperature": "300 K",
        "unit_in_source": "cm²/s, printed as greater than 11.1"
      },
      "method": "Lower limit printed in a trade article that reports Element Six product data",
      "status": "ground",
      "source": "mwrf-diafilm",
      "where": "Thermal diffusivity at 300 K list, row TM200",
      "source_detail": {
        "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
        "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
        "year": 2017,
        "kind": "web",
        "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Corrosive chemicals and hostile environments",
      "headline": "CVD diamond is chemically inert and the manufacturer says it can operate in corrosive environments.",
      "effect": "Element Six says its CVD diamond components can operate in highly corrosive and hostile environments and that diamond ATR prisms give the longest lifetimes. The brochure gives no test data, so this is a manufacturer statement, not a measured corrosion rate.",
      "rating": "none",
      "conditions": {
        "basis": "manufacturer statement; no chemical, temperature or time given"
      },
      "source": "e6-optics",
      "where": "Page 2, section Unparalleled chemical inertness"
    },
    {
      "environment": "Rain impact",
      "headline": "Rain impact damage threshold velocity is printed as 525 m/s for polycrystalline optical grade.",
      "effect": "Element Six prints a rain impact DTV of 525 m/s for polycrystalline optical grade and of 457 - 533 m/s for single crystal. The brochure does not define the abbreviation DTV or give the test set-up in its printed text.",
      "rating": "low",
      "conditions": {
        "grade": "polycrystalline optical grade (525) and single crystal (457 - 533)",
        "unit_in_source": "m s-1"
      },
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Rain impact DTV (m s-1)"
    },
    {
      "environment": "Sand erosion",
      "headline": "Sand erosion is 2.1 ± 0.6 mg/kg at 100 m/s for polycrystalline optical grade.",
      "effect": "Element Six prints a sand erosion value of 2.1 ± 0.6 mg kg-1 at 100 m s-1 with C300/600 sand for polycrystalline optical grade. The brochure gives no value for single crystal, and no exposure time is printed.",
      "rating": "low",
      "conditions": {
        "grade": "polycrystalline CVD diamond, optical grade",
        "sand": "C300/600",
        "velocity": "100 m/s"
      },
      "source": "e6-optics",
      "where": "Page 5, table CVD diamond properties, row Sand erosion"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "PubChem's record for the element carbon (CID 5462310) aggregates ECHA C&L notifications for carbon, EC 231-153-3, with GHS07, signal word 'Warning', H319 'Causes serious eye irritation' and H335 'May cause respiratory irritation'. A second ECHA notification for carbon, EC 610-410-7, is listed as Not Classified. These are element-level notifications, not a classification of CVD diamond.",
        "ghs": [
          "H319",
          "H335"
        ],
        "source": "pubchem-carbon-ghs",
        "where": "GHS Classification section, ECHA C&L entries (Reference 26 and Reference 29)"
      },
      {
        "text": "PACE Technologies safety data sheet for Diamond Powders (date revised 7/21/2025) is a metallographic abrasive SDS. It states 'Not a hazardous substance or mixture' under GHS, with pictogram, signal word and hazard statements all N/A, and gives precautionary statement 'P261-Avoid breathing dust.' Section 4 says the material is 'not likely to be hazardous by inhalation'. The SDS does not say the diamond is synthetic or CVD-grown.",
        "ghs": [],
        "source": "pace-diamond-sds",
        "where": "Section 2 Hazard(s) Identification; Section 4 First-Aid Measures, Inhalation; header date revised"
      }
    ],
    "failure_risks": [
      {
        "mode": "Sand erosion of an exposed diamond surface",
        "trigger": "Sand impacting at 100 m/s, in the test used by Element Six",
        "consequence": "Element Six prints 2.1 ± 0.6 mg/kg of mass loss for polycrystalline optical grade. The brochure does not say how much erosion would matter for a given part.",
        "severity": "low",
        "source": "e6-optics",
        "where": "Page 5, row Sand erosion"
      },
      {
        "mode": "Fracture under load, with wide strength spread",
        "trigger": "Tensile stress on a single-crystal part",
        "consequence": "Element Six prints a fracture stress of 3500 MPa with a Weibull modulus of 2.5 for single-crystal optical grade and optical plus. The brochure does not explain what the modulus means for a part's strength.",
        "severity": "moderate",
        "source": "e6-optics",
        "where": "Page 5, row Fracture stress (MPa) [Weibull modulus]"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Element Six says CVD diamond can be processed to virtually any shape, and that windows and mounts can be made with water or air cooling if required.",
        "source": "e6-optics",
        "where": "Page 2 section Sizes and shapes; page 4 section Collaboration in applications development"
      },
      {
        "text": "Element Six lists maximum sizes of up to Ø 135 mm and 3 mm thick for polycrystalline optical grades, and plates up to 7 x 7 x 2 mm for single crystal.",
        "source": "e6-optics",
        "where": "Page 2 section Sizes and shapes"
      }
    ],
    "mitigations": []
  },
  "uses": [
    {
      "application": "thermal-control",
      "device": "Heat spreaders for high-power GaN transistors, MMICs and laser diodes",
      "example": "Element Six Diafilm heat spreaders are stated for high-power, high-density circuits, including GaN discrete transistors, MMICs and laser diodes.",
      "source": "mwrf-diafilm",
      "where": "Article, applications paragraph"
    },
    {
      "application": "optics-and-cameras",
      "device": "Optical windows for high-power CO2 and solid-state lasers",
      "example": "Element Six lists optical windows and lenses for high-power CO2 lasers and high-power solid-state lasers, and says CVD diamond windows allow much higher laser power densities than other materials.",
      "source": "e6-optics",
      "where": "Page 3, section Optical windows in high power lasers; page 4, table Example applications"
    },
    {
      "application": "electronics-and-chips",
      "device": "RF and microwave windows in high-power gyrotrons",
      "example": "Element Six says CVD RF diamond windows are used in nuclear fusion experiments, in gyrotrons above 2 MW and as containment windows in waveguides.",
      "source": "e6-optics",
      "where": "Page 4, section Optical microwave CVD diamond at the frontiers of science"
    },
    {
      "application": "thermal-control",
      "device": "Heat sinks for high-power laser diodes and AlGaN/GaN HEMT transistors",
      "example": "A 2019 open-access chapter lists CVD diamond heat sinking components for transistor high power devices and high power laser diodes, and names AlGaN/GaN HEMTs produced on CVD diamond substrates.",
      "source": "intech-cvd-heat-sinks",
      "where": "Section CVD diamond as a heat spreader or in devices"
    }
  ],
  "supply": [
    {
      "subject": "Synthetic industrial diamond (manufactured bort, grit, dust and powder)",
      "producers": [],
      "critical_lists": [],
      "recycling": "USGS: in 2025 about 15 million carats of diamond bort, grit, dust and powder were recycled, and at least two companies recovered used industrial diamond material. Manufactured production was estimated at 160 million carats.",
      "substitutes": [
        "USGS: cubic boron nitride, fused aluminum oxide and silicon carbide can compete with industrial diamond in some applications."
      ],
      "source": "usgs-mcs2026-diamond",
      "where": "Domestic Production and Use; Events, Trends, and Issues; Recycling; Substitutes"
    },
    {
      "subject": "Natural industrial diamond (mine production, shown for contrast)",
      "producers": [
        {
          "country": "Russia",
          "share_percent": 42,
          "year": 2025
        },
        {
          "country": "Congo (Kinshasa)",
          "share_percent": 18,
          "year": 2025
        },
        {
          "country": "Botswana",
          "share_percent": 14,
          "year": 2025
        },
        {
          "country": "Zimbabwe",
          "share_percent": 13,
          "year": 2025
        },
        {
          "country": "South Africa",
          "share_percent": 8,
          "year": 2025
        }
      ],
      "critical_lists": [],
      "recycling": "Synthetic diamond accounts for more than 99 % of global industrial diamond production and consumption, and natural diamond for less than 1 % of industrial diamond used (USGS).",
      "substitutes": [],
      "source": "usgs-mcs2026-diamond",
      "where": "Events, Trends, and Issues (natural production shares as printed, 16 of 38 million carats worldwide); World Natural Industrial Diamond Mine Production and Reserves; World Resources"
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Element Six, Optics: CVD diamond brochure (March 2021)",
      "type": "datasheet",
      "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
      "year": 2021
    },
    {
      "title": "Coherent, Single Crystal Diamond, Optical Grade (SCD-O) datasheet",
      "type": "datasheet",
      "url": "https://www.coherent.com/content/dam/coherent/site/en/resources/datasheet/optics/single-crystal-diamond-optical-grade.pdf",
      "year": 2026
    },
    {
      "title": "Jack Browne, Diamond is precious for thermal dissipation (Microwaves & RF, 2 March 2017)",
      "type": "report",
      "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
      "year": 2017
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Diamond (Industrial)",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-diamond.pdf",
      "year": 2026
    },
    {
      "title": "Wikipedia: Diamond (crystal structure, synthesis)",
      "type": "database",
      "url": "https://en.wikipedia.org/wiki/Diamond"
    },
    {
      "title": "PubChem compound record CID 5462310 (carbon element record)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5462310"
    },
    {
      "title": "PACE Technologies, Safety Data Sheet, Diamond Powders (date revised 7/21/2025)",
      "type": "sds",
      "url": "https://www.metallographic.com/sds/Diamond-powders.pdf",
      "year": 2025
    },
    {
      "title": "PubChem GHS Classification, compound record CID 5462310 (carbon), JSON view",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5462310/JSON?heading=GHS+Classification"
    },
    {
      "title": "Vieira da Silva Neto, Fraga and Trava-Airoldi (2019), Development, Properties, and Applications of CVD Diamond-Based Heat Sinks",
      "type": "paper",
      "url": "https://intechopen.com/chapters/66249",
      "year": 2019
    }
  ],
  "gaps": [
    "No hazard classification for CVD diamond itself was found. The hazard entries use an SDS for a diamond abrasive powder, which does not say the diamond is synthetic, and PubChem's element-level ECHA notifications for carbon, which conflict with the SDS. Both are recorded side by side.",
    "No CAS number for synthetic diamond was read. The PubChem name lookup returned CID 5462310, which is the carbon element record and not a diamond-specific entry.",
    "No atomic-oxygen erosion or reaction data, and no outgassing or total mass loss test for CVD diamond, were found in the pages read in this run.",
    "No oxidation limit or graphitisation temperature in air was found in the pages read, so the maximum service temperature is not recorded.",
    "No radiation (total dose or displacement damage) data for CVD diamond were looked up.",
    "The Element Six Diamond Handbook is cited on page 5 of the brochure but was not opened, so its references are not recorded.",
    "The Diafilm TM150 and TM180 thermal conductivity values at 300 K and 425 K (printed in the trade article) were not entered; only TM100 and TM200 at 300 K are recorded. Thermal conductivity at 425 K is recorded for the Element Six optical and RF grades only.",
    "Thermal conductivity at cryogenic temperatures and at 1000 K was not found in the pages read.",
    "Wikipedia gives 900 to 2320 W m-1 K-1 as a range for identifying diamond with no temperature or condition stated, so it is not entered as a property.",
    "Critical-mineral list status for industrial diamond was not read. The USGS diamond summary does not state a critical-mineral listing, and the 2025 USGS critical list was not checked in this run.",
    "Per-country shares of synthetic industrial diamond production are not printed in the USGS summary; only the rank order and the combined share of about 99 % are recorded.",
    "Element Six lists 1050 for Young's modulus with no unit on page 5; the GPa range from the Diafilm article is entered instead.",
    "The Element Six nucleation and growth values (800 [10], 400 [15] and so on) and the 633 transmittance row were left out because the brochure does not print a clear unit or meaning for them.",
    "Property names not in the canonical list (hardness, absorption_coefficient, birefringence, emittance, fracture_stress, sand_erosion, thermal_diffusivity, refractive_index_temperature_coefficient) use snake_case names. The Element Six rain impact DTV abbreviation is not defined in the brochure.",
    "Only one open-access chapter (2019, IntechOpen) was read for CVD diamond heat sinks, and no peer-reviewed journal paper with measured CVD diamond data was read. A 2019 MDPI article (DOI path 2571-9637/5/1/8) appeared in search but could not be fetched, so it is not used."
  ],
  "story": {
    "why": "CVD diamond has the highest thermal conductivity of any material, according to Element Six. Its polycrystalline optical grade is printed at greater than 2200 W/(m·K) at 300 K, and its RF grade at greater than 2000 W/(m·K) at 300 K. A Coherent single-crystal optical grade sheet prints at least 2200 W/(m·K) with no temperature given. That is why the material is used as a heat spreader under high-power electronics and as a window in high-power lasers.",
    "uses": [
      {
        "where": "Heat spreaders",
        "line": "Element Six Diafilm heat spreaders are stated for high-power, high-density circuits, including GaN discrete transistors, MMICs and laser diodes. The Diafilm TM200 grade is printed at greater than 2000 W/(m·K) at 300 K."
      },
      {
        "where": "Laser windows",
        "line": "Element Six lists optical windows for high-power CO2 and solid-state lasers, and says CVD diamond windows allow much higher laser power densities than other materials."
      },
      {
        "where": "RF windows",
        "line": "Element Six says CVD RF diamond windows are used in nuclear fusion experiments, in gyrotrons above 2 MW and as containment windows in waveguides."
      },
      {
        "where": "Laser and power-electronics heat sinks",
        "line": "A 2019 open-access chapter says CVD diamond heat sinks are used for high-power laser diodes and transistor high power devices, and names AlGaN/GaN HEMTs on CVD diamond substrates (Vieira da Silva Neto et al., 2019)."
      }
    ],
    "can_do": [
      {
        "label": "Carry heat",
        "line": "Element Six prints greater than 2200 W/(m·K) at 300 K for polycrystalline optical grade and for single-crystal optical grade. At 425 K it prints greater than 1600 W/(m·K) for the polycrystalline optical grade.",
        "benchmark": "thermal_conductivity",
        "scope": "material",
        "value": "greater than 2200 W/(m·K) at 300 K"
      },
      {
        "label": "Stay dimensionally stable",
        "line": "The coefficient of thermal expansion is 1.0 ppm/K at 300 K and 4.4 ppm/K at 1000 K, per Element Six. The Diafilm article prints 1.0 ± 0.1 ppm/K at 300 K.",
        "benchmark": "cte",
        "scope": "material",
        "value": "1.0 ppm/K at 300 K"
      },
      {
        "label": "Weight",
        "line": "Density is printed as 3.52 x 10³ kg m⁻³ in the Element Six brochure and as 3.52 x 10³ kg/m³ in the Diafilm article.",
        "benchmark": "density",
        "scope": "material",
        "value": "3.52 g/cm3"
      },
      {
        "label": "Pass light",
        "line": "Polycrystalline optical grade transmits 71.4 % through 1 mm of material over 8 to 200 µm, per Element Six.",
        "benchmark": "transmittance",
        "scope": "material",
        "value": "71.4 % at 1 mm"
      },
      {
        "label": "Hard",
        "line": "Polycrystalline CVD diamond is printed at a hardness of 81 ± 18 GPa, and single crystal at 70 - 120 GPa.",
        "benchmark": "hardness",
        "scope": "material",
        "value": "81 ± 18 GPa"
      }
    ],
    "compare": "The Element Six brochure prints thermal conductivity above 2000 W/(m·K) at 300 K for the RF and optical grades, and the Coherent single-crystal sheet prints at least 2200 W/(m·K), and the Diafilm article gives 1000 and 2000 W/(m·K) for the TM100 and TM200 grades. The two sources give different specific heat figures, 520 J/(kg·K) at 300 K in the trade article and 0.536 J/g-K at 25 °C on the Coherent sheet, so read them with their temperatures in view. For birefringence the Element Six table gives 1e-4 for its single-crystal optical grade, while the Coherent sheet gives less than 5e-5, so grades and sources need to be matched before comparing.",
    "compare_rows": [
      {
        "label": "Thermal conductivity",
        "benchmark": "thermal_conductivity",
        "scope": "material"
      },
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Thermal expansion",
        "benchmark": "cte",
        "scope": "material"
      }
    ],
    "handling": [
      "Specify the grade, because polycrystalline and single-crystal values differ, and the RF grade is lower than the optical grade for thermal conductivity.",
      "Check the size limits before design: Ø 135 mm by 3 mm for polycrystalline optical grade, and 7 x 7 x 2 mm for single crystal.",
      "Read the supplier's SDS for the exact product before use. The PACE SDS covers a diamond abrasive powder, not CVD plate or window material."
    ],
    "good_for": [
      "Heat spreading: greater than 2200 W/(m·K) at 300 K for the optical grades, per Element Six.",
      "High-power laser windows: absorption at 10.6 µm below 0.07 cm-1 for polycrystalline optical grade.",
      "Erosion resistance: sand erosion of 2.1 ± 0.6 mg/kg at 100 m/s for polycrystalline optical grade."
    ],
    "watch_out": [
      "Size: polycrystalline optical windows top out at Ø 135 mm and 3 mm thick, and single-crystal plates at 7 x 7 x 2 mm.",
      "Strength spread: a Weibull modulus of 2.5 with a fracture stress of 3500 MPa for single crystal, and the brochure does not explain the scatter.",
      "No atomic-oxygen, oxidation or radiation data were read for this profile. The hazard entries come from an abrasive-powder SDS and element-level PubChem notifications, not from a CVD plate SDS."
    ],
    "verdict": "CVD diamond is printed at greater than 2200 W/(m·K) at 300 K for the Element Six optical grades and at least 2200 W/(m·K) on the Coherent sheet, and the Diafilm article gives greater than 2000 W/(m·K) at 300 K for the TM200 grade. Its size limits, the 2.5 Weibull modulus on fracture stress, and the missing CVD-specific hazard and space-environment data are the main gaps.",
    "recipe": {
      "line": "Diamond is pure carbon with a cubic crystal structure (Wikipedia). Synthetic diamond can be grown from hydrocarbon gases by chemical vapour deposition (Wikipedia). Coherent describes its single-crystal optical grade as made by plasma-enhanced chemical vapour deposition (Coherent datasheet).",
      "parts": [
        {
          "name": "Carbon",
          "symbol": "C",
          "role": "The whole material. The PubChem carbon element record prints a molecular weight of 12.011.",
          "atoms": 1,
          "atomic_weight": 12.011
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The sources give two different pictures. An SDS for a diamond abrasive powder says the material is not a hazardous substance, and PubChem's element-level notifications for carbon carry eye and respiratory irritation statements.",
        "points": [
          {
            "label": "Substance",
            "line": "PubChem's carbon element record aggregates ECHA notifications with GHS07, signal word Warning, H319 \"Causes serious eye irritation\" and H335 \"May cause respiratory irritation\". These are for carbon, not for CVD diamond."
          },
          {
            "label": "Dust and handling",
            "line": "The PACE SDS for diamond powders gives precautionary statement P261 \"Avoid breathing dust.\" and says the material is not likely to be hazardous by inhalation. The brochure does not describe dust or powder hazards for the optical and RF grades; it describes the material as chemically inert."
          }
        ],
        "level": 1,
        "verdict": "Mixed; no classification for CVD diamond itself was read"
      },
      {
        "title": "If it fails",
        "lead": "These are failure routes found in the sources. The sand erosion and fracture figures are measurements printed by the manufacturer.",
        "points": [
          {
            "label": "Sand erosion",
            "line": "Element Six prints 2.1 ± 0.6 mg/kg of sand erosion at 100 m/s for polycrystalline optical grade, with C300/600 sand."
          },
          {
            "label": "Fracture",
            "line": "Element Six prints a fracture stress of 3500 MPa for single-crystal optical grade, with a Weibull modulus of 2.5, and does not say what the modulus means for a part."
          },
          {
            "label": "Rain",
            "line": "Element Six prints a rain impact DTV of 525 m/s for polycrystalline optical grade and of 457 - 533 m/s for single crystal."
          }
        ]
      },
      {
        "title": "Handling and storage",
        "points": [
          {
            "label": "Size",
            "line": "Element Six lists polycrystalline optical windows up to Ø 135 mm and 3 mm thick, and single-crystal plates up to 7 x 7 x 2 mm."
          },
          {
            "label": "Mounting",
            "line": "Element Six says windows and mounts can be made with water or air cooling if required."
          }
        ]
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 33,
    "unreachable": 1,
    "caveats": 5,
    "note": "Values were read by an AI assistant on 2026-11-01 from the Element Six brochure (page 5 table read from a rendered image), the Coherent SCD-O datasheet, the Microwaves & RF article (WebFetch), the USGS Mineral Commodity Summaries 2026 diamond text, and Wikipedia (WebFetch). Added in the hazard and use pass: the PACE diamond powder SDS (rev. 7/21/2025), the PubChem GHS Classification JSON for CID 5462310, and the 2019 IntechOpen CVD diamond heat sink chapter. Unreachable: PubChem diamond page (browser check); MDPI page (403, and a mirror refused connection). Caveats: the Element Six and Coherent sources disagree on single-crystal birefringence and on the 1064 nm refractive index; the Young's modulus unit comes from a trade article; the Diafilm values are from a trade article, not the datasheet; no peer-reviewed paper was read."
  },
  "sources": {
    "e6-optics": {
      "title": "Element Six, Optics: CVD diamond brochure (March 2021), pages 2 to 5",
      "url": "https://terpconnect.umd.edu/~antonsen/ENEE681-lectures/element_six_optics_brochure_1.pdf",
      "year": 2021,
      "kind": "datasheet",
      "license": "Manufacturer brochure, cited, not reproduced"
    },
    "coherent-scd-o": {
      "title": "Coherent, Single Crystal Diamond, Optical Grade (SCD-O) datasheet",
      "url": "https://www.coherent.com/content/dam/coherent/site/en/resources/datasheet/optics/single-crystal-diamond-optical-grade.pdf",
      "year": 2026,
      "kind": "datasheet",
      "license": "Manufacturer datasheet, cited, not reproduced"
    },
    "mwrf-diafilm": {
      "title": "Jack Browne, Diamond is precious for thermal dissipation, Microwaves & RF, 2 March 2017",
      "url": "https://www.mwrf.com/technologies/article/21848133/diamond-is-precious-for-thermal-dissipation",
      "year": 2017,
      "kind": "web",
      "license": "Trade article reporting Element Six Diafilm data, cited, not reproduced"
    },
    "usgs-mcs2026-diamond": {
      "title": "Mineral Commodity Summaries 2026, Diamond (Industrial)",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-diamond.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "wikipedia-diamond": {
      "title": "Diamond (crystal structure, synthesis), Wikipedia",
      "url": "https://en.wikipedia.org/wiki/Diamond",
      "kind": "web",
      "license": "CC BY-SA 4.0 (cited, not reproduced)"
    },
    "pubchem-carbon": {
      "title": "PubChem compound record CID 5462310 (carbon element record)",
      "id": "CID 5462310",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/5462310",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "pace-diamond-sds": {
      "title": "PACE Technologies, Safety Data Sheet, Diamond Powders (date revised 7/21/2025)",
      "url": "https://www.metallographic.com/sds/Diamond-powders.pdf",
      "year": 2025,
      "kind": "datasheet",
      "license": "Manufacturer SDS, cited, not reproduced"
    },
    "pubchem-carbon-ghs": {
      "title": "PubChem compound record CID 5462310 (carbon), GHS Classification section, JSON view",
      "id": "CID 5462310",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/5462310/JSON?heading=GHS+Classification",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "intech-cvd-heat-sinks": {
      "title": "Vieira da Silva Neto, Fraga and Trava-Airoldi (2019), Development, Properties, and Applications of CVD Diamond-Based Heat Sinks",
      "id": "DOI 10.5772/intechopen.85349",
      "url": "https://intechopen.com/chapters/66249",
      "year": 2019,
      "kind": "paper",
      "license": "open-access chapter (IntechOpen), cited, not reproduced"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/cvd-diamond/"
}