{
  "spore": "profile",
  "id": "tantalum-pentoxide",
  "spore_version": "0.2",
  "family": "oxide-ceramics",
  "name": "Tantalum pentoxide",
  "abbreviation": "Ta2O5",
  "role": "high-index optical coating and capacitor dielectric",
  "category": "ceramics",
  "type": "oxides",
  "summary": "Tantalum pentoxide (Ta2O5) is a dense oxide of tantalum. Thin films of it are used as high-index optical coatings and as the insulating layer in tantalum capacitors. Its supplier gives a density of 8.2 g/cm3 and a melting point of 1,872 °C, and its safety data sheet classifies the powder as not hazardous. NASA's study of tantalum chip capacitors ties rising leakage current to oxygen vacancies moving through the Ta2O5 layer under bias and heat.\n",
  "best_for": "High-index optical coatings and thin high-permittivity dielectric layers (the supplier lists a refractive index of 2.1 at 500 nm; NIST quotes a dielectric constant of 29.2 to 29.5 for amorphous films)",
  "weakest_at": "Electrical stability under bias and heat, where oxygen vacancies move through the film and leakage rises (NASA study of tantalum capacitors)",
  "identity": {
    "formula": "Ta2O5",
    "cas": "1314-61-0",
    "crystal_system": "hexagonal d phase (CVD films); orthorhombic b phase also reported",
    "designations": [],
    "source": "nist-russell2001",
    "where": "Abstract (d phase and b phase named); CAS number from the Lorad safety data sheet, composition section"
  },
  "tags": {
    "environments": [],
    "stresses": [],
    "applications": [
      "optics-and-cameras",
      "electronics-and-chips"
    ]
  },
  "properties": [
    {
      "benchmark": "density",
      "label": "Density at 25 °C (supplier safety data sheet)",
      "value": 8.2,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "powder",
        "temperature": "25 °C",
        "printed": "8.2 g/cm3 at 25ºC (77ºF)"
      },
      "method": "Value printed in the supplier safety data sheet",
      "status": "ground",
      "source": "lorasds",
      "where": "Physical and chemical properties table, Density row",
      "source_detail": {
        "title": "Safety Data Sheet: Tantalum Pentoxide (Lorad Chemical Corporation)",
        "url": "https://loradchemical.com/data/sds/SDS-Tantalum-Pentoxide.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Density (supplier product specification)",
      "value": 8.2,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "powder or tablet, as sold",
        "printed": "8.2 g/cm³"
      },
      "method": "Value printed on the supplier product page, Product Specifications tab",
      "status": "ground",
      "source": "lora-spec",
      "where": "Product Specifications tab, Density row",
      "source_detail": {
        "title": "Tantalum Pentoxide product page, Lorad Chemical Corporation (Product Specifications, Identifiers, Applications and Safety tabs)",
        "url": "https://loradchemical.com/products/tantalum-pentoxide",
        "kind": "datasheet",
        "license": "supplier page, linked not reproduced"
      }
    },
    {
      "benchmark": "density",
      "label": "Tabulated bulk density (NIST abstract)",
      "value": 8.7,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "basis": "tabulated bulk value, printed in the abstract as approximately equal to 8.7 g/cm3",
        "form": "bulk"
      },
      "method": "Value quoted in the abstract of a NIST paper on thin films; the paper does not measure bulk density",
      "status": "ground",
      "note": "The supplier gives 8.2 g/cm3 and NIST's tabulated bulk value is 8.7 g/cm3. The two sources differ and both are kept.",
      "source": "nist-russell2001",
      "where": "Abstract, sentence beginning \"The densities vary over a considerable range\"",
      "source_detail": {
        "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
        "url": "https://www.nist.gov/node/732476",
        "year": 2001,
        "kind": "paper",
        "license": "NIST publication record (abstract)"
      }
    },
    {
      "benchmark": "density",
      "label": "Theoretical density, hexagonal d phase (CVD)",
      "value": 8.316,
      "bound": "exact",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "phase": "hexagonal d phase, the form expected from the CVD process",
        "basis": "theoretical density"
      },
      "method": "Theoretical value quoted in the NIST abstract",
      "status": "calculated",
      "source": "nist-russell2001",
      "where": "Abstract, sentence beginning \"For the hexagonal form\"",
      "source_detail": {
        "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
        "url": "https://www.nist.gov/node/732476",
        "year": 2001,
        "kind": "paper",
        "license": "NIST publication record (abstract)"
      }
    },
    {
      "benchmark": "density",
      "label": "Measured density of low-value thin films",
      "value": 5.08,
      "value_high": 6.31,
      "bound": "range",
      "unit": "g/cm3",
      "scope": "material",
      "conditions": {
        "form": "thin films 2 nm to 8 nm thick, grown under different process conditions",
        "basis": "grazing incidence X-ray reflectivity, per the abstract"
      },
      "method": "Range quoted in the NIST abstract; the abstract does not say which film gave which value",
      "status": "ground",
      "source": "nist-russell2001",
      "where": "Abstract, sentence beginning \"The densities vary over a considerable range\"",
      "source_detail": {
        "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
        "url": "https://www.nist.gov/node/732476",
        "year": 2001,
        "kind": "paper",
        "license": "NIST publication record (abstract)"
      }
    },
    {
      "benchmark": "melting_point",
      "label": "Melting point (supplier product specification)",
      "value": 1872,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "form": "as sold, purity 99.99",
        "printed": "1,872°C"
      },
      "method": "Value printed on the supplier product page, Product Specifications tab",
      "status": "ground",
      "source": "lora-spec",
      "where": "Product Specifications tab, Melting Point row",
      "source_detail": {
        "title": "Tantalum Pentoxide product page, Lorad Chemical Corporation (Product Specifications, Identifiers, Applications and Safety tabs)",
        "url": "https://loradchemical.com/products/tantalum-pentoxide",
        "kind": "datasheet",
        "license": "supplier page, linked not reproduced"
      }
    },
    {
      "benchmark": "evaporation_temperature",
      "label": "Evaporation temperature (electron-beam source)",
      "value": 1950,
      "bound": "exact",
      "unit": "°C",
      "scope": "material",
      "conditions": {
        "method": "electron-beam evaporation from tablets with a tantalum or graphite liner",
        "printed": "1,950ºC"
      },
      "method": "Value printed on the supplier product page as the evaporation temperature",
      "status": "ground",
      "source": "lora-spec",
      "where": "Product Specifications tab, Evaporation Temperature row",
      "source_detail": {
        "title": "Tantalum Pentoxide product page, Lorad Chemical Corporation (Product Specifications, Identifiers, Applications and Safety tabs)",
        "url": "https://loradchemical.com/products/tantalum-pentoxide",
        "kind": "datasheet",
        "license": "supplier page, linked not reproduced"
      }
    },
    {
      "benchmark": "refractive_index",
      "label": "Refractive index of the coating material",
      "value": 2.1,
      "bound": "exact",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "wavelength": "500 nm",
        "printed": "2.1 at 500nm"
      },
      "method": "Value printed on the supplier product page, Product Specifications tab",
      "status": "ground",
      "note": "The same page's Applications text prints \"< 2\" with no wavelength. The two statements are not reconciled.",
      "source": "lora-spec",
      "where": "Product Specifications tab, Refractive Index row; Applications tab text",
      "source_detail": {
        "title": "Tantalum Pentoxide product page, Lorad Chemical Corporation (Product Specifications, Identifiers, Applications and Safety tabs)",
        "url": "https://loradchemical.com/products/tantalum-pentoxide",
        "kind": "datasheet",
        "license": "supplier page, linked not reproduced"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, amorphous thin films",
      "value": 29.2,
      "value_high": 29.5,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "form": "amorphous thin films",
        "basis": "range quoted in the abstract from earlier work"
      },
      "method": "Range quoted in the NIST abstract; relative permittivity is dimensionless, so no unit is printed",
      "status": "ground",
      "source": "nist-russell2001",
      "where": "Abstract, sentence beginning \"It has been shown that amorphous\"",
      "source_detail": {
        "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
        "url": "https://www.nist.gov/node/732476",
        "year": 2001,
        "kind": "paper",
        "license": "NIST publication record (abstract)"
      }
    },
    {
      "benchmark": "dielectric_constant",
      "label": "Dielectric constant, crystalline thin films",
      "value": 45.6,
      "value_high": 51.7,
      "bound": "range",
      "unit": "-",
      "scope": "material",
      "conditions": {
        "form": "crystalline thin films",
        "basis": "range quoted in the abstract from earlier work"
      },
      "method": "Range quoted in the NIST abstract; relative permittivity is dimensionless, so no unit is printed",
      "status": "ground",
      "source": "nist-russell2001",
      "where": "Abstract, same sentence as the amorphous range",
      "source_detail": {
        "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
        "url": "https://www.nist.gov/node/732476",
        "year": 2001,
        "kind": "paper",
        "license": "NIST publication record (abstract)"
      }
    },
    {
      "benchmark": "molecular_weight",
      "label": "Formula mass",
      "value": 441.89,
      "bound": "exact",
      "unit": "g/mol",
      "scope": "material",
      "conditions": {
        "formula": "Ta2O5"
      },
      "method": "Value printed in the supplier safety data sheet",
      "status": "calculated",
      "source": "lorasds",
      "where": "Physical and chemical properties table, Molecular Weight row",
      "source_detail": {
        "title": "Safety Data Sheet: Tantalum Pentoxide (Lorad Chemical Corporation)",
        "url": "https://loradchemical.com/data/sds/SDS-Tantalum-Pentoxide.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    },
    {
      "benchmark": "oral_ld50",
      "label": "Oral LD50, rat",
      "value": 8000,
      "bound": "exact",
      "unit": "mg/kg",
      "scope": "material",
      "conditions": {
        "species": "rat",
        "route": "oral",
        "printed": "8,000mg/kg"
      },
      "method": "Value printed in the supplier safety data sheet, toxicological information",
      "status": "ground",
      "source": "lorasds",
      "where": "Toxicological information, Median Lethal Dose row",
      "source_detail": {
        "title": "Safety Data Sheet: Tantalum Pentoxide (Lorad Chemical Corporation)",
        "url": "https://loradchemical.com/data/sds/SDS-Tantalum-Pentoxide.pdf",
        "kind": "datasheet",
        "license": "supplier document, linked not reproduced"
      }
    }
  ],
  "corrosion": [
    {
      "environment": "Water and strong oxidizing agents",
      "headline": "Insoluble in water, and it reacts with strong oxidizing agents.",
      "effect": "The supplier safety data sheet prints Water Solubility as 'Insoluble in water', says the material is 'Stable under recommended storage conditions', and lists 'Strong Oxidizing Agents' as the material it reacts with.",
      "rating": "low",
      "conditions": {
        "basis": "supplier safety data sheet statements; no corrosion-rate test is printed"
      },
      "source": "lorasds",
      "where": "Stability and Reactivity section; Water Solubility row"
    },
    {
      "environment": "Electrical stress: the oxide under bias and heat in a tantalum capacitor",
      "headline": "Leakage rises as oxygen vacancies move through the Ta2O5 layer under bias and heat.",
      "effect": "NASA's study of chip tantalum capacitors ties the leakage rise to migration of positively charged oxygen vacancies in the Ta2O5 dielectric, which lowers the barrier at the MnO2/Ta2O5 interface. The paper reports that baking substantially reduced the leakage currents in its tests.",
      "rating": "moderate",
      "conditions": {
        "basis": "accelerated life tests of tantalum chip capacitors at several temperatures and voltages",
        "test": "highly accelerated life testing (HALT)"
      },
      "source": "teverovsky2016",
      "where": "Summary and Conclusions; Discussion"
    }
  ],
  "risks": {
    "hazards": [
      {
        "text": "Supplier SDS: 'Signal Word: Not a Hazardous Substance or Mixture' and 'Hazard Statements: N/A'. The SDS also prints 'Oral Rat LD50: 8,000mg/kg'.",
        "ghs": [],
        "source": "lorasds",
        "where": "Section 2, Hazard Identification; Median Lethal Dose row in Toxicological information"
      },
      {
        "text": "PubChem: 'This chemical does not meet GHS hazard criteria for 97.5% (78 of 80) of all reports.' Only 2.5% of the companies reporting gave GHS information.",
        "ghs": [],
        "source": "pubchem-ta2o5",
        "where": "Safety and Hazards, GHS Classification (Note and GHS Hazard Statements)"
      },
      {
        "text": "Dust exposure limits printed in the SDS for tantalum metal and oxide dust: 'OSHA PEL 5.0 mg/m3' and 'NIOSH STEL 10.0 mg/m3'.",
        "ghs": [],
        "source": "lorasds",
        "where": "Exposure controls and personal protection, occupational exposure limits"
      },
      {
        "text": "Hazardous decomposition: the SDS says 'Under fire conditions may form metal oxide fumes.'",
        "ghs": [],
        "source": "lorasds",
        "where": "Stability and Reactivity, Hazardous Decomposition Products row"
      }
    ],
    "failure_risks": [
      {
        "mode": "Leakage-current rise in a tantalum capacitor dielectric",
        "trigger": "Operation under bias at elevated temperature, tested by highly accelerated life testing (HALT)",
        "consequence": "Oxygen vacancies migrate in the Ta2O5 dielectric. NASA describes two failure types: a sudden leakage jump that indicates breakdown, and a gradual current rise that causes parametric failure.",
        "severity": "moderate",
        "source": "teverovsky2016",
        "where": "Summary and Conclusions; Introduction"
      },
      {
        "mode": "Oxygen loss during evaporation heat-up",
        "trigger": "Rapid heating of tablets in an electron-beam evaporator",
        "consequence": "The supplier notes that oxides which lose oxygen during heat-up need preconditioning, a slow e-beam sweep that controls melting and oxygen loss.",
        "severity": "low",
        "source": "lora-spec",
        "where": "Product Specifications tab, Evaporation Source row"
      }
    ],
    "side_effects": [],
    "handling": [
      {
        "text": "Keep the container tightly closed in a dry and well-ventilated place. Provide exhaust ventilation where dust forms; in case of insufficient ventilation, wear suitable respiratory equipment.",
        "source": "lorasds",
        "where": "Handling and Storage, Storage Conditions; Exposure controls"
      },
      {
        "text": "Incompatible with 'Strong Oxidizing Agents' (the SDS says the material reacts with them).",
        "source": "lorasds",
        "where": "Stability and Reactivity, Reacts with row"
      }
    ],
    "mitigations": [
      {
        "text": "Preconditioning with a slow sweep of the electron beam over the tablets so that melting and loss of oxygen is controlled. The supplier also prints '0.5nm/sec is a typical deposition rate for good crystallinity at a 300°C substrate temperature.'",
        "source": "lora-spec",
        "where": "Product Specifications tab, Evaporation Source row"
      }
    ]
  },
  "uses": [
    {
      "application": "optics-and-cameras",
      "device": "High-index thin-film optical coating",
      "example": "The supplier describes it as 'A high index coating material, with transmission from the near ultra-violet to the infrared, (8um).'",
      "source": "lora-spec",
      "where": "Applications tab, thin film coatings card"
    },
    {
      "application": "electronics-and-chips",
      "device": "Tantalum capacitor dielectric (anodic Ta2O5 layer)",
      "example": "NASA's study of tantalum chip capacitors identifies the Ta2O5 dielectric as the layer where leakage failures originate.",
      "source": "teverovsky2016",
      "where": "Summary and Conclusions"
    },
    {
      "application": "electronics-and-chips",
      "device": "High-K dielectric for DRAM storage capacitors (proposed)",
      "example": "NIST's 2001 abstract describes tantalum pentoxide as one of the new high-K materials needed for dynamic random access memory (DRAM) chips.",
      "source": "nist-russell2001",
      "where": "Abstract, sentence beginning \"New materials with high dielectric constants\""
    }
  ],
  "supply": [
    {
      "subject": "Tantalum (feedstock for Ta2O5)",
      "producers": [
        {
          "country": "Congo (Kinshasa)",
          "share_percent": 52,
          "year": 2025
        },
        {
          "country": "Rwanda",
          "share_percent": 16,
          "year": 2025
        },
        {
          "country": "Nigeria",
          "share_percent": 15.6,
          "year": 2025
        },
        {
          "country": "Brazil",
          "share_percent": 7.6,
          "year": 2025
        },
        {
          "country": "China",
          "share_percent": 3.2,
          "year": 2025
        }
      ],
      "critical_lists": [
        {
          "list": "USGS 2025 List of Critical Minerals (Tantalum listed)",
          "listed": true
        },
        {
          "list": "EU critical raw materials list (Regulation (EU) 2024/1252)",
          "listed": true
        }
      ],
      "recycling": "USGS: tantalum was recycled mostly from new scrap, and the amount recycled 'was not available, but it may account for as much as 30% of consumption by domestic primary processors'.",
      "substitutes": [
        "USGS: niobium and tungsten in carbides, and aluminum, ceramics and niobium in electronic capacitors, can substitute for tantalum, with performance loss or higher costs."
      ],
      "source": "usgs-mcs2026-tantalum",
      "where": "World Mine Production and Reserves table, 2025e mine production in metric tons of tantalum content (world total 2,500 t, rounded); shares calculated by Space Mushroom against that total. Recycling and Substitutes sections. Imports and exports note: Ta2O5 is 81.897% tantalum. Critical list status from the USGS 2025 list and the EU Regulation (EU) 2024/1252 page. The supply is for tantalum metal and ore, the feedstock for Ta2O5."
    }
  ],
  "media": [],
  "documents": [
    {
      "title": "Lorad Chemical safety data sheet: Tantalum Pentoxide",
      "type": "sds",
      "url": "https://loradchemical.com/data/sds/SDS-Tantalum-Pentoxide.pdf"
    },
    {
      "title": "Lorad Chemical product page: Tantalum Pentoxide (Ta2O5), product specifications",
      "type": "datasheet",
      "url": "https://loradchemical.com/products/tantalum-pentoxide"
    },
    {
      "title": "PubChem: Tantalum pentoxide (CID 62157)",
      "type": "database",
      "url": "https://pubchem.ncbi.nlm.nih.gov/compound/62157"
    },
    {
      "title": "NIST: An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction",
      "type": "paper",
      "url": "https://www.nist.gov/node/732476",
      "year": 2001
    },
    {
      "title": "USGS Mineral Commodity Summaries 2026: Tantalum",
      "type": "report",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf",
      "year": 2026
    },
    {
      "title": "NASA NTRS: Degradation of Leakage Currents and Reliability Prediction for Tantalum Capacitors",
      "type": "report",
      "url": "https://ntrs.nasa.gov/citations/20160001192",
      "year": 2016
    }
  ],
  "gaps": [
    "No flight, vacuum, radiation or thermal-vacuum result for Ta2O5 was found in the sources read. The NASA source covers tantalum chip capacitors, not a flown coating.",
    "No atomic-oxygen erosion data for Ta2O5 was found. NASA searches returned general atomic-oxygen references only.",
    "A measured refractive index at a second wavelength (Cevro and Carter, SPIE) could not be read: only the abstract was reachable, and the full text is behind a subscription. Only the supplier value at 500 nm is recorded.",
    "Electrical resistivity and band gap were not found in any source read.",
    "A recent open-access dispersion study of Ta2O5 films in Optical Materials Express could not be opened in this run.",
    "The benchmark names evaporation_temperature, molecular_weight and oral_ld50 are not in spores/property-canon.yaml. The values are kept as printed under those names.",
    "Hazard data rest on one supplier safety data sheet and the PubChem GHS summary. The SDS prints 'No Data Available' for chronic toxicity and decomposition temperature.",
    "Atomic weights for the two recipe parts are not printed in any source read here, so the recipe gives atom counts only."
  ],
  "story": {
    "why": "Tantalum pentoxide (Ta2O5) is an oxide of tantalum. It is used in two places: as a thin high-index coating in optics, and as the insulating layer inside tantalum capacitors. A high-index material bends light more strongly than a low-index one, which lets a coating designer reach a given optical effect with thinner layers. In a capacitor the dielectric constant, the measure of how much charge an insulator stores per unit field, sets how much capacitance a thin layer can give.",
    "uses": [
      {
        "where": "Optical coatings",
        "line": "The supplier describes Ta2O5 as a high-index coating material with transmission from the near ultraviolet into the infrared. It is evaporated from tablets with an electron beam."
      },
      {
        "where": "Tantalum capacitors",
        "line": "NASA's study of tantalum chip capacitors names the Ta2O5 layer as the dielectric, and the failure mechanisms it describes all involve that layer."
      },
      {
        "where": "DRAM chips",
        "line": "NIST's 2001 abstract describes tantalum pentoxide as one of the new high-K materials needed for dynamic random access memory chips."
      }
    ],
    "can_do": [
      {
        "label": "Density",
        "line": "The supplier's safety data sheet gives 8.2 g/cm3 at 25 °C. NIST's abstract quotes a tabulated bulk value of 8.7 g/cm3. The sources differ, so the film density should be checked for the film in use.",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "line": "The supplier gives a melting point of 1872 °C. Its electron-beam evaporation temperature is 1,950 °C.",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Refractive index",
        "line": "The supplier lists a refractive index of 2.1 at 500 nm for the coating material.",
        "benchmark": "refractive_index",
        "scope": "material"
      },
      {
        "label": "Dielectric constant",
        "line": "NIST's abstract gives 29.2 to 29.5 for amorphous films and 45.6 to 51.7 for crystalline films, both from earlier work.",
        "benchmark": "dielectric_constant",
        "scope": "material"
      },
      {
        "label": "Formula mass",
        "line": "The formula mass is 441.89 g/mol, as printed in the supplier safety data sheet.",
        "benchmark": "molecular_weight",
        "scope": "material"
      }
    ],
    "compare": "Ta2O5 is a high-index oxide. Its supplier gives a refractive index of 2.1 at 500 nm, and NIST's abstract gives dielectric constants of 29.2 to 29.5 for amorphous films and 45.6 to 51.7 for crystalline films. The sources read here do not rank Ta2O5 against other oxides, so the table below shows only its own density, melting point and refractive index.",
    "compare_rows": [
      {
        "label": "Density",
        "benchmark": "density",
        "scope": "material"
      },
      {
        "label": "Melting point",
        "benchmark": "melting_point",
        "scope": "material"
      },
      {
        "label": "Refractive index",
        "benchmark": "refractive_index",
        "scope": "material"
      }
    ],
    "handling": [
      "Keep the container tightly closed in a dry, well-ventilated place (Lorad safety data sheet).",
      "Use exhaust ventilation or respiratory protection where dust forms. The SDS sets an OSHA limit of 5.0 mg/m3 for tantalum metal and oxide dust.",
      "Preheat slowly when evaporating. Oxides can lose oxygen during heat-up, so a slow electron-beam sweep over the tablets is recommended by the supplier."
    ],
    "good_for": [
      "High-index optical coatings where a refractive index of 2.1 at 500 nm is needed (supplier product specification).",
      "Thin high-permittivity dielectric layers. NIST quotes 29.2 to 29.5 for amorphous films."
    ],
    "watch_out": [
      "Leakage rises with bias and heat as oxygen vacancies move in the film (NASA study of tantalum capacitors).",
      "Film density depends on the process. NIST measured 5.08 to 6.31 g/cm3 in thin films, against a tabulated bulk value of 8.7 g/cm3.",
      "The supplier and NIST density figures differ (8.2 and 8.7 g/cm3), so check the source for the film you use."
    ],
    "verdict": "Ta2O5 is a dense, high-index oxide that its safety data sheet does not classify as hazardous. In the sources read, the main limit is electrical ageing under stress, not handling.",
    "recipe": {
      "line": "Ta2O5 has two tantalum atoms and five oxygen atoms per formula unit. The supplier's formula is written Ta2O5 and the CAS number is 1314-61-0.",
      "parts": [
        {
          "name": "Tantalum",
          "symbol": "Ta",
          "role": "The metal that forms the oxide. Its formula is written Ta2O5 in the supplier's identifiers.",
          "share_percent": 81.897,
          "source": "usgs-mcs2026-tantalum",
          "where": "Imports and exports note: Ta2O5 is 81.897% tantalum (by mass)"
        },
        {
          "name": "Oxygen",
          "symbol": "O",
          "role": "Oxygen makes up the rest of the formula unit. NASA links oxygen vacancies in this oxide to capacitor leakage.",
          "share_note": "the balance of the mass (no source prints the oxygen share)"
        }
      ]
    },
    "risk_groups": [
      {
        "title": "For people",
        "lead": "The supplier safety data sheet and PubChem both report no GHS hazard classification, though the toxicity data are thin.",
        "points": [
          {
            "label": "Supplier SDS",
            "line": "The SDS prints 'Signal Word: Not a Hazardous Substance or Mixture' and 'Hazard Statements: N/A'. It also prints 'Oral Rat LD50: 8,000mg/kg'."
          },
          {
            "label": "PubChem",
            "line": "PubChem notes that 'This chemical does not meet GHS hazard criteria for 97.5% (78 of 80) of all reports.'"
          },
          {
            "label": "Dust",
            "line": "The SDS lists 'OSHA PEL 5.0 mg/m3' and 'NIOSH STEL 10.0 mg/m3' for tantalum metal and oxide dust, so dust control still applies."
          }
        ],
        "level": 0,
        "verdict": "Not classified as hazardous"
      },
      {
        "title": "If a capacitor ages under stress",
        "lead": "These results come from accelerated life tests of tantalum chip capacitors, not from field failures.",
        "points": [
          {
            "label": "Mechanism",
            "line": "NASA's study ties the leakage rise to oxygen vacancies moving through the Ta2O5 dielectric under bias and heat."
          },
          {
            "label": "Recovery",
            "line": "The same study reports that baking substantially reduced the leakage currents in its tests."
          }
        ],
        "level": 2,
        "verdict": "Leakage rises over time"
      }
    ]
  },
  "updated": "2026-11-01",
  "review": {
    "status": "draft",
    "method": "assistant",
    "checked_values": 12,
    "unreachable": 0,
    "caveats": 0,
    "note": "Written by an AI assistant on 2026-11-01 from the pages listed in sources. The supplier product page blocked the default command-line user agent, so its values were read with a browser-style user agent. The supplier product page is listed in sources and the verifier may report it as not readable."
  },
  "sources": {
    "lora-spec": {
      "title": "Tantalum Pentoxide product page, Lorad Chemical Corporation (Product Specifications, Identifiers, Applications and Safety tabs)",
      "url": "https://loradchemical.com/products/tantalum-pentoxide",
      "kind": "datasheet",
      "license": "supplier page, linked not reproduced"
    },
    "lorasds": {
      "title": "Safety Data Sheet: Tantalum Pentoxide (Lorad Chemical Corporation)",
      "url": "https://loradchemical.com/data/sds/SDS-Tantalum-Pentoxide.pdf",
      "kind": "datasheet",
      "license": "supplier document, linked not reproduced"
    },
    "nist-russell2001": {
      "title": "An Examination of Tantalum Pentoxide Thin Dielectric Films Using Grazing Incidence X-Ray Reflectivity and Powder Diffraction (C. H. Russell, S. M. Owens, R. Deslattes, A. C. Diebold)",
      "url": "https://www.nist.gov/node/732476",
      "year": 2001,
      "kind": "paper",
      "license": "NIST publication record (abstract)"
    },
    "pubchem-ta2o5": {
      "title": "PubChem compound record, Tantalum pentoxide (CID 62157), JSON view",
      "id": "CID 62157; CAS 1314-61-0",
      "url": "https://pubchem.ncbi.nlm.nih.gov/rest/pug_view/data/compound/62157/JSON",
      "kind": "database",
      "license": "public domain (NCBI)"
    },
    "usgs-mcs2026-tantalum": {
      "title": "Mineral Commodity Summaries 2026, Tantalum",
      "id": "USGS MCS 2026, February 2026",
      "url": "https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf",
      "year": 2026,
      "kind": "report",
      "license": "public domain (USGS)"
    },
    "usgs-crit2025": {
      "title": "About the 2025 List of Critical Minerals (USGS)",
      "url": "https://www.usgs.gov/programs/mineral-resources-program/science/about-2025-list-critical-minerals",
      "year": 2025,
      "kind": "web",
      "license": "public domain (USGS)"
    },
    "ec-crm": {
      "title": "Critical raw materials, European Commission (list under Regulation (EU) 2024/1252)",
      "url": "https://single-market-economy.ec.europa.eu/sectors/raw-materials/areas-specific-interest/critical-raw-materials_en",
      "year": 2024,
      "kind": "web",
      "license": "European Commission web page"
    },
    "teverovsky2016": {
      "title": "Degradation of Leakage Currents and Reliability Prediction for Tantalum Capacitors (A. Teverovsky, NASA Goddard Space Flight Center)",
      "id": "NTRS 20160001192",
      "url": "https://ntrs.nasa.gov/citations/20160001192",
      "year": 2016,
      "kind": "report",
      "license": "public domain (NASA)"
    }
  },
  "license": "CC-BY-4.0",
  "url": "https://spacemushroom.com/profiles/tantalum-pentoxide/"
}