Tantalum Ta
Ta (element, atomic number 73)
Tantalum is the element Ta (atomic number 73), a dense, very high-melting refractory metal.
Evidence level
2 of 5
Lab-measured
- 0Predicted only. No one has made it, or no measurement exists.
- 1Calculated. Only calculated or predicted values from sources.
- 2Lab-measured. Measured properties with their conditions stated.
- 3Space-relevant tests. Measured in conditions relevant to space, such as vacuum or atomic oxygen.
- 4Ground-qualified. Qualified for an application on the ground.
- 5Flown or field-proven. Flight or field results exist.
Recipe, share of the weight
- Ta 100.0%Tantalum
Best for
Dense, high-melting spot shielding in thin sheet, such as the approximately 1 mm tantalum vault plate on NASA's Europa Clipper
Weakest at
Mass: the 16650 kg/m3 density makes it heavy for large areas, and the vault plate is only a local shield, not a full enclosure
Risk at a glance
- People Low. Not assessed in this run
- If it fails No data. No failure risks recorded
- Corrosion Severe. Unsuitable: attacked by hydrofluoric acid, the main exception.
Quick facts: Ta
| Property | Value | Basis |
|---|---|---|
| Density | 16.6 g/cm³ | 1 sourced value |
| Young's modulus | 186 GPa | 1 sourced value |
| Hardness (Brinell) | 800 MN/m2 | 1 sourced value |
| Thermal conductivity | 57 W/(m·K) | 1 sourced value |
| Melting point | 3,017 °C | 1 sourced value |
| Electrical resistivity | 1.4e-7 Ω·m | 1 sourced value |
What is the density of Tantalum?
Tantalum has a density of 16.6 g/cm³. The source and test conditions are listed in the properties table on this page.
What is the thermal conductivity of Tantalum?
Tantalum has a thermal conductivity of 57 W/(m·K). The source and test conditions are listed in the properties table on this page.
What is the melting point of Tantalum?
Tantalum has a melting point of 3,017 °C. The source and test conditions are listed in the properties table on this page.
What is the Young's modulus of Tantalum?
Tantalum has a Young's modulus of 186 GPa. The source and test conditions are listed in the properties table on this page.
What is the hardness of Tantalum?
Tantalum has a Brinell hardness of 800 MN/m2. The source and test conditions are listed in the properties table on this page.
What is Tantalum used for?
Uses recorded in the sources include Spot shield on spacecraft electronics vault; Tantalum capacitor anode; Spot shield (NIST attenuation context).
Why it exists
Tantalum is dense and melts at 3017 degC, so a thin sheet can block radiation locally without a heavy enclosure. The NASA Europa Clipper vault plate is the sourced example of it on a spacecraft.
Recipe
Ta (element, atomic number 73); body-centred cubic alpha phase at all temperatures up to melting
Tantalum is the element Ta, atomic number 73, a single-element metal with no alloying in pure form. Its ore is mainly tantalite, (Fe,Mn)Ta2O6, usually mined with columbite, the niobium ore. Ore is concentrated by gravity separation, leached with hydrofluoric acid and sulfuric or hydrochloric acid, and purified by solvent extraction into an organic solvent. Niobium is removed by lowering the acid ionic strength, and the tantalum is then precipitated with ammonia and calcined to Ta2O5. The metal is made by reducing the purified salt or oxide; The first metal was made by reducing tantalum chloride in hydrogen, as de Marignac did in the 19th century. The metal powder is pressed into pellets for capacitors.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Tantalum Ta | 1 | 100.0% | The whole material. WebElements prints the relative atomic mass as 180.94788 (2). Natural tantalum is almost entirely one isotope, with a very small share of a metastable isomer (Wikipedia). |
Weight shares are calculated from standard atomic weights.
What it can do
Give a dense,
Give a dense, high-melting shield in thin sheet on a spacecraft.
Serve as the
Serve as the anode material of capacitors, which take the largest share of tantalum demand.
How it compares
Tantalum is 16650 kg/m3 and melts at 3017 degC; aluminium, the usual spacecraft shield metal, is far lighter and melts much lower. Its photon mass attenuation is 4.302 cm2/g at 0.1 MeV, against 0.170 cm2/g for aluminium, and 0.06567 cm2/g against 0.06146 cm2/g at 1 MeV (NIST, per gram). Per gram the two are close at 1 MeV, so tantalum wins mainly on density for a thin plate.
The same measurements for each material, so you can compare them. Each row names the key condition under the value; the full conditions and methods are in the numbered notes under Technical details. Compare every grade in the family.
| Measurement | Ta |
|---|---|
| Thermal behavior and safety | |
| Melting pointValue listed in the WebElements tantalum page | 3017 °C2 |
| Thermal conductivity | 57 W/(m·K)7 |
| Coefficient of linear thermal expansion | 6.3×10^-6 1/K8 |
| Physical and electrical | |
| Density of solid | 16650 kg/m31 |
| Electrical resistivity | 1.35×10^-7 ohm·m9 |
| Vickers hardness | 873 MN/m210 |
| Brinell hardness | 800 MN/m211 |
| Other measurements | |
| Boiling pointValue listed in the WebElements tantalum page | 5458 °C3 |
| Young's modulus | 186 GPa4 |
| Bulk modulus | 200 GPa5 |
| Poisson's ratio | 0.34 dimensionless6 |
| Velocity of sound | 3400 m/s12 |
| Atomic numberValue listed in the WebElements tantalum page | 73 dimensionless |
| Mass attenuation coefficient at 0.1 MeV | 4.302 cm²/g13 |
| Mass attenuation coefficient at 1 MeV | 0.06567 cm²/g14 |
| Mass attenuation coefficient at 10 MeV | 0.04717 cm²/g15 |
| Mass attenuation coefficient at 0.1 MeV (aluminium) | 0.1704 cm²/g16 |
| Mass attenuation coefficient at 1 MeV (aluminium) | 0.06146 cm²/g17 |
| Mass attenuation coefficient at 10 MeV (aluminium) | 0.02318 cm²/g18 |
Why choose it, and why not
Good for
- Local radiation spot shields around sensitive electronics.
Watch out for
- Its mass is high for large areas.
- Hydrofluoric acid and hydrogen uptake in hot acids limit its use in chemical service.
- The NIST values are per gram of material; no dose reduction in a spacecraft vault was sourced in this run.
Tantalum is a dense, high-melting metal used as local spot shielding and as capacitor anode material. This deepened draft adds recipe, supply shares from the USGS 2026 summary, corrosion, hazards from PubChem, and NIST photon attenuation against aluminium.
Technical details
For scientists and researchers. Everything above comes from the record below: every number with its method, its conditions and its source.
Notes
The method, full conditions and any caveat for the numbered rows above.
| # | Measurement | Method | Conditions | Caveat |
|---|---|---|---|---|
| 1 | Density of solid | Value listed in the WebElements physical properties table | form solid elemental tantalumtemperature not stated on the page | — |
| 2 | Melting point | — | form elemental tantalumpressure not statedprinted as 3290 K | — |
| 3 | Boiling point | — | form elemental tantalumpressure not statedprinted as 5731 K | — |
| 4 | Young's modulus | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 5 | Bulk modulus | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 6 | Poisson's ratio | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 7 | Thermal conductivity | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 8 | Coefficient of linear thermal expansion | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 9 | Electrical resistivity | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 10 | Vickers hardness | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 11 | Brinell hardness | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 12 | Velocity of sound | Value listed in the WebElements physical properties table | form elemental tantalumtemperature not stated on the page | — |
| 13 | Mass attenuation coefficient at 0.1 MeV | NIST X-ray mass attenuation table, total mass attenuation (mu/rho) | energy 0.1 MeVphoton yeselement tantalum | — |
| 14 | Mass attenuation coefficient at 1 MeV | NIST X-ray mass attenuation table, total mass attenuation (mu/rho) | energy 1 MeVphoton yeselement tantalum | — |
| 15 | Mass attenuation coefficient at 10 MeV | NIST X-ray mass attenuation table, total mass attenuation (mu/rho) | energy 10 MeVphoton yeselement tantalum | — |
| 16 | Mass attenuation coefficient at 0.1 MeV (aluminium) | NIST X-ray mass attenuation table, aluminium comparison | energy 0.1 MeVphoton yeselement aluminium | — |
| 17 | Mass attenuation coefficient at 1 MeV (aluminium) | NIST X-ray mass attenuation table, aluminium comparison | energy 1 MeVphoton yeselement aluminium | — |
| 18 | Mass attenuation coefficient at 10 MeV (aluminium) | NIST X-ray mass attenuation table, aluminium comparison | energy 10 MeVphoton yeselement aluminium | — |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at room temperature | not rated | Forms a very dense Ta2O5 oxide layer that protects the metal.1 |
| Most acids and aqua regia below 150 degC | not rated | Almost immune to attack by aqua regia below 150 degC.2 |
| Hydrofluoric acid | severe | Unsuitable: attacked by hydrofluoric acid, the main exception.3 |
| Hot sulfuric acid and hot alkaline solutions | moderate | Hot sulfuric acid and hot alkaline solutions also corrode it.4 |
| Hot acids (hydrogen charging) | moderate | Hydrogen enters the lattice and makes the metal brittle.5 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at room temperature | Samaterials says that when exposed to air, tantalum forms a very dense oxide layer (Ta2O5), which protects the base metal. Wikipedia describes the oxide as the basis of tantalum capacitors, where the thin layer acts as the dielectric. | basis qualitative; no thickness or time given |
| 2 | Most acids and aqua regia below 150 degC | Wikipedia says tantalum is almost completely immune to attack by the normally aggressive aqua regia at temperatures below 150 degC, and is inert to most acids. | temperature below 150 °Cbasis Wikipedia summary, no test data |
| 3 | Hydrofluoric acid | Samaterials lists hydrofluoric acid below 60 percent as not resistant, with no temperature given, and says tantalum is unsuitable for use in hydrofluoric acid. Wikipedia says it dissolves in hydrofluoric acid and in acidic solutions with fluoride ion. | concentration below 60 percenttemperature not stated |
| 4 | Hot sulfuric acid and hot alkaline solutions | Wikipedia says tantalum is inert to most acids except hydrofluoric acid and hot sulfuric acid, and that hot alkaline solutions also cause corrosion. Molten potassium hydroxide also dissolves it. | temperature hot, not statedbasis Wikipedia summary |
| 5 | Hot acids (hydrogen charging) | Samaterials says that if tantalum is exposed to chemical aggression, hydrogen enters its metal lattice and the material becomes brittle. No hydrogen concentration is given on the page. | basis qualitative statement, no concentration given |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
This profile has no sourced health data for tantalum metal.
- Metal in use
- Tantalum metal is used as a sealed shield and inside capacitors. No hazard classification was read in this run, so none is stated here.
If it fails
No sourced failure mode was found in this run.
- Mechanical
- The sheet is a local shield. Its density is 16650 kg/m3, and its Vickers hardness is 873 MN/m2.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Hydrogen embrittlement in hot acids | Chemical aggression that lets hydrogen enter the latticeThe metal becomes brittle (samaterials, no concentration given). |
| Attack by hydrofluoric acid | Contact with hydrofluoric acid below 60 percentTantalum is not resistant and is unsuitable for the service (samaterials). |
Handling and storage
- Keep away from heat, sparks and open flames, and ground equipment when handling powder or swarf (PubChem P210, P240, P241).
- Wear protective gloves and avoid breathing dust (PubChem P280, H335).
- Keep away from hydrofluoric acid and hot alkaline solutions (corrosion section).
Supply and geography
How common the raw materials are and where they come from.
Tantalum
Share of demand from electronics: about 55 percent in 2019 (Paumanok estimate); averaged 50 to 70 percent of total tantalum demand over the past 30 years
- Recycling
- Not sourced in this profile
Tantalum mine production, 2025 estimate (USGS)
World mine total 2,500 t (rounded). Congo (Kinshasa) 1,300 t, Rwanda 400 t, Nigeria 390 t, China 80 t, Australia 50 t. Shares below are each printed value divided by the printed world total.
- Top producers (2025)
- Congo (Kinshasa) 52%, Rwanda 16%, Nigeria 15.6%, China 3.2%, Australia 2%
- Recycling
- USGS: recycled mostly from new scrap; may account for as much as 30 percent of consumption by domestic primary processors. US recycled amount not available.
- Substitutes
- niobium and tungsten in carbides; aluminum, ceramics and niobium in electronic capacitors; glass, molybdenum, nickel, niobium, platinum, stainless steel, titanium and zirconium in corrosion-resistant uses; hafnium, iridium, molybdenum, niobium, rhenium and tungsten in high-temperature uses
Documents
Datasheets, safety data sheets, papers and standards you can open.
| Document | Type | Year |
|---|---|---|
| USGS Mineral Commodity Summaries 2026: Tantalum | report | 2026 |
| PubChem: Tantalum (CID 23956), GHS classification | database | 2026 |
Full record
The complete spore, as stored. Free to reuse under CC-BY-4.0. Images keep the licence shown with each one.
Show the full YAML
spore: profile
id: tantalum
spore_version: 0.2
family: refractory-metals
name: Tantalum
abbreviation: Ta
role: dense refractory metal (radiation spot shielding, capacitor anodes)
category: shielding
type: spot-shields
summary: |
Tantalum is the element Ta (atomic number 73), a dense, very high-melting refractory metal. Its solid density is 16650 kg/m3 and its melting point is 3017 degC (3290 K), so it is far denser than aluminium and close to tungsten in stopping power per unit thickness. It is used as thin spot shields around sensitive electronics on spacecraft, and as the anode material of tantalum capacitors, which take the largest share of its industrial demand.
best_for: Dense, high-melting spot shielding in thin sheet, such as the approximately 1 mm tantalum vault plate on NASA's Europa Clipper
weakest_at: 'Mass: the 16650 kg/m3 density makes it heavy for large areas, and the vault plate is only a local shield, not a full enclosure'
identity:
formula: Ta (element, atomic number 73); body-centred cubic alpha phase at all temperatures up to melting
source: webelements-physics
where: Atomic structure and solid-state properties sections of the WebElements tantalum page; the page lists atomic number 73 on the main tantalum page
tags:
environments: []
stresses:
- total-radiation-dose
applications:
- radiation-shielding
- electronics-and-chips
properties:
- benchmark: density
label: Density of solid
value: 16650
unit: kg/m3
scope: material
conditions:
form: solid elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Density of solid
- benchmark: melting_point
label: Melting point
value: 3017
unit: degC
scope: material
conditions:
form: elemental tantalum
pressure: not stated
printed_as: 3290 K
method: Value listed in the WebElements tantalum page
status: ground
source: webelements-main
where: Melting point row, printed as 3290 [3017 degC (5463 degF)] K
- benchmark: boiling_point
label: Boiling point
value: 5458
unit: degC
scope: material
conditions:
form: elemental tantalum
pressure: not stated
printed_as: 5731 K
method: Value listed in the WebElements tantalum page
status: ground
source: webelements-main
where: Boiling point row, printed as 5731 [5458 degC (9856 degF)] K
- benchmark: youngs_modulus
label: Young's modulus
value: 186
unit: GPa
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Young's modulus
- benchmark: bulk_modulus
label: Bulk modulus
value: 200
unit: GPa
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Bulk modulus
- benchmark: poissons_ratio
label: Poisson's ratio
value: 0.34
unit: dimensionless
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Poisson's ratio
- benchmark: thermal_conductivity
label: Thermal conductivity
value: 57
unit: W/(m·K)
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Thermal conductivity
- benchmark: thermal_expansion
label: Coefficient of linear thermal expansion
value: 0.0000063
unit: 1/K
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Coefficient of linear thermal expansion
- benchmark: electrical_resistivity
label: Electrical resistivity
value: 1.35e-7
unit: ohm·m
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Electrical resistivity (printed as 13.5 x 10-8 ohm m)
- benchmark: vickers_hardness
label: Vickers hardness
value: 873
unit: MN/m2
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Vickers hardness
- benchmark: brinell_hardness
label: Brinell hardness
value: 800
unit: MN/m2
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Brinell hardness
- benchmark: speed_of_sound
label: Velocity of sound
value: 3400
unit: m/s
scope: material
conditions:
form: elemental tantalum
temperature: not stated on the page
method: Value listed in the WebElements physical properties table
status: ground
source: webelements-physics
where: Physical properties table, row Velocity of sound
- benchmark: atomic_number
label: Atomic number
value: 73
unit: dimensionless
scope: material
conditions:
element: tantalum
method: Value listed in the WebElements tantalum page
status: ground
source: webelements-main
where: Atomic number row
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 0.1 MeV
value: 4.302
unit: cm2/g
scope: material
conditions:
energy: 0.1 MeV
photon: 'yes'
element: tantalum
method: NIST X-ray mass attenuation table, total mass attenuation (mu/rho)
status: ground
source: nist-xray-z73
where: Row 1.00000E-01 MeV, mu/rho column
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 1 MeV
value: 0.06567
unit: cm2/g
scope: material
conditions:
energy: 1 MeV
photon: 'yes'
element: tantalum
method: NIST X-ray mass attenuation table, total mass attenuation (mu/rho)
status: ground
source: nist-xray-z73
where: Row 1.00000E+00 MeV, mu/rho column
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 10 MeV
value: 0.04717
unit: cm2/g
scope: material
conditions:
energy: 10 MeV
photon: 'yes'
element: tantalum
method: NIST X-ray mass attenuation table, total mass attenuation (mu/rho)
status: ground
source: nist-xray-z73
where: Row 1.00000E+01 MeV, mu/rho column
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 0.1 MeV (aluminium)
value: 0.1704
unit: cm2/g
scope: material
conditions:
energy: 0.1 MeV
photon: 'yes'
element: aluminium
method: NIST X-ray mass attenuation table, aluminium comparison
status: ground
source: nist-xray-z13
where: Row 1.00000E-01 MeV, mu/rho column
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 1 MeV (aluminium)
value: 0.06146
unit: cm2/g
scope: material
conditions:
energy: 1 MeV
photon: 'yes'
element: aluminium
method: NIST X-ray mass attenuation table, aluminium comparison
status: ground
source: nist-xray-z13
where: Row 1.00000E+00 MeV, mu/rho column
- benchmark: mass_attenuation_coefficient
label: Mass attenuation coefficient at 10 MeV (aluminium)
value: 0.02318
unit: cm2/g
scope: material
conditions:
energy: 10 MeV
photon: 'yes'
element: aluminium
method: NIST X-ray mass attenuation table, aluminium comparison
status: ground
source: nist-xray-z13
where: Row 1.00000E+01 MeV, mu/rho column
uses:
- application: radiation-shielding
device: Spot shield on spacecraft electronics vault
example: 'NASA Europa Clipper: a tantalum vault plate about 1 mm thick, 18 by 28 cm, part of the structure that protects the orbiter electronics from Jupiter radiation'
source: nasa-europa-clipper
where: Placing the Europa Clipper vault plate article, material and purpose paragraphs
- application: electronics-and-chips
device: Tantalum capacitor anode
example: Electronics takes about 55 percent of tantalum demand (2019 estimate by Paumanok), mainly as capacitor anodes
source: passive-components-tantalum
where: Paragraph on 2019 consumption and electronics share
- application: radiation-shielding
device: Spot shield (NIST attenuation context)
example: Photon mass attenuation values in the properties list compare tantalum with aluminium per gram.
source: nist-xray-z73
where: Mass attenuation table, Z = 73
supply:
- subject: Tantalum
abundance: 'Share of demand from electronics: about 55 percent in 2019 (Paumanok estimate); averaged 50 to 70 percent of total tantalum demand over the past 30 years'
recycling: Not sourced in this profile
substitutes: []
source: passive-components-tantalum
where: Paragraph on 2019 consumption and multi-year electronics share
- subject: Tantalum mine production, 2025 estimate (USGS)
abundance: World mine total 2,500 t (rounded). Congo (Kinshasa) 1,300 t, Rwanda 400 t, Nigeria 390 t, China 80 t, Australia 50 t. Shares below are each printed value divided by the printed world total.
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: China
share_percent: 3.2
year: 2025
- country: Australia
share_percent: 2
year: 2025
recycling: 'USGS: recycled mostly from new scrap; may account for as much as 30 percent of consumption by domestic primary processors. US recycled amount not available.'
substitutes:
- niobium and tungsten in carbides
- aluminum, ceramics and niobium in electronic capacitors
- glass, molybdenum, nickel, niobium, platinum, stainless steel, titanium and zirconium in corrosion-resistant uses
- hafnium, iridium, molybdenum, niobium, rhenium and tungsten in high-temperature uses
source: usgs-mcs-2026-tantalum
where: Salient Statistics table (2025e apparent consumption 890 t, net import reliance 100 percent); World Mine Production table, 2025e column; Recycling and Substitutes paragraphs
documents:
- title: 'USGS Mineral Commodity Summaries 2026: Tantalum'
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
year: 2026
- title: 'PubChem: Tantalum (CID 23956), GHS classification'
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/Tantalum
year: 2026
media: []
corrosion:
- environment: Air at room temperature
headline: Forms a very dense Ta2O5 oxide layer that protects the metal.
effect: Samaterials says that when exposed to air, tantalum forms a very dense oxide layer (Ta2O5), which protects the base metal. Wikipedia describes the oxide as the basis of tantalum capacitors, where the thin layer acts as the dielectric.
rating: unknown
conditions:
basis: qualitative; no thickness or time given
source: samaterials-tantalum-corrosion
where: Introduction paragraph on oxide layer; Wikipedia Tantalum, Applications, capacitors paragraph
- environment: Most acids and aqua regia below 150 degC
headline: Almost immune to attack by aqua regia below 150 degC.
effect: Wikipedia says tantalum is almost completely immune to attack by the normally aggressive aqua regia at temperatures below 150 degC, and is inert to most acids.
rating: unknown
conditions:
temperature: below 150 degC
basis: Wikipedia summary, no test data
source: wikipedia-tantalum
where: Properties section, paragraph on corrosion by acids
- environment: Hydrofluoric acid
headline: 'Unsuitable: attacked by hydrofluoric acid, the main exception.'
effect: Samaterials lists hydrofluoric acid below 60 percent as not resistant, with no temperature given, and says tantalum is unsuitable for use in hydrofluoric acid. Wikipedia says it dissolves in hydrofluoric acid and in acidic solutions with fluoride ion.
rating: severe
conditions:
concentration: below 60 percent
temperature: not stated
source: samaterials-tantalum-corrosion
where: Acid resistance table, row Hydrofluoric acid; Wikipedia Properties section
- environment: Hot sulfuric acid and hot alkaline solutions
headline: Hot sulfuric acid and hot alkaline solutions also corrode it.
effect: Wikipedia says tantalum is inert to most acids except hydrofluoric acid and hot sulfuric acid, and that hot alkaline solutions also cause corrosion. Molten potassium hydroxide also dissolves it.
rating: moderate
conditions:
temperature: hot, not stated
basis: Wikipedia summary
source: wikipedia-tantalum
where: Properties section, corrosion paragraphs
- environment: Hot acids (hydrogen charging)
headline: Hydrogen enters the lattice and makes the metal brittle.
effect: Samaterials says that if tantalum is exposed to chemical aggression, hydrogen enters its metal lattice and the material becomes brittle. No hydrogen concentration is given on the page.
rating: moderate
conditions:
basis: qualitative statement, no concentration given
source: samaterials-tantalum-corrosion
where: Hydrogen embrittlement paragraph
risks:
hazards:
- text: PubChem aggregates GHS reports for tantalum (CID 23956). The main entry, 56 percent of 455 company reports, gives H228 (flammable solid), signal word Danger, class Flam. Sol. 2. 44 percent of reports do not meet GHS criteria. PubChem does not separate bulk metal from powder, so check the SDS for the form you handle.
ghs:
- 'H228: Flammable solid'
source: pubchem-tantalum
where: Safety and Hazards, GHS Classification
- text: Other ECHA C&L notifications listed by PubChem give H335 (may cause respiratory irritation, signal word Warning) and H302 (harmful if swallowed, signal word Warning).
ghs:
- 'H335: May cause respiratory irritation'
- 'H302: Harmful if swallowed'
source: pubchem-tantalum
where: Safety and Hazards, GHS Classification, ECHA entries
- text: Precautionary statement codes listed by PubChem include P210 (keep away from heat, sparks and open flames), P240 and P241 (grounding, explosion-proof equipment), P280 (protective equipment), P370+P378 (in case of fire, use suitable extinguishing media) and P407.
ghs: []
source: pubchem-tantalum
where: Safety and Hazards, Precautionary Statement Codes
failure_risks:
- mode: Hydrogen embrittlement in hot acids
trigger: Chemical aggression that lets hydrogen enter the lattice
consequence: The metal becomes brittle (samaterials, no concentration given).
source: samaterials-tantalum-corrosion
where: Hydrogen embrittlement paragraph
- mode: Attack by hydrofluoric acid
trigger: Contact with hydrofluoric acid below 60 percent
consequence: Tantalum is not resistant and is unsuitable for the service (samaterials).
source: samaterials-tantalum-corrosion
where: Acid resistance table
side_effects: []
handling:
- text: Keep away from heat, sparks and open flames, and ground equipment when handling powder or swarf (PubChem P210, P240, P241).
source: pubchem-tantalum
where: Safety and Hazards, Precautionary Statement Codes
- text: Wear protective gloves and avoid breathing dust (PubChem P280, H335).
source: pubchem-tantalum
where: Safety and Hazards, Precautionary Statement Codes
- text: Keep away from hydrofluoric acid and hot alkaline solutions (corrosion section).
source: pubchem-tantalum
where: Corrosion section, hydrofluoric acid row
mitigations: []
gaps:
- 'Dose reduction or areal density for a tantalum vault against the Jupiter radiation environment: the Juno/Europa vault paper was not found by search in this run, so no mission attenuation figure is recorded.'
- 'Corrosion rates in mm/year or mpy: no source with a rate was read in this run.'
- 'The hydrogen concentration threshold for embrittlement (a patent gives 100 ppm): the patent page was not fetched, so no value is recorded.'
- Mozambique and Brazil mine production rows in the USGS 2026 table are garbled in the PDF text, so they are left out of the shares.
- Melting and boiling point and density are printed at the temperature stated in the source only; the density temperature is not stated.
- Capacitor-share figures (about 55 percent electronics, 2019) are industry estimates from the Paumanok passive-components article, not a USGS statistic.
- 'US production: none, USGS 2025e apparent consumption 890 t, net import reliance 100 percent.'
- 'Sensitive-electronics radiation dose tests for a tantalum vault: none sourced.'
sources:
webelements-physics:
title: 'Tantalum - 73Ta: physical properties'
url: https://winter.group.shef.ac.uk/webelements/tantalum/physics.html
year: 2024
kind: database
license: WebElements (University of Sheffield), free online reference
webelements-main:
title: 'Tantalum - 73Ta: the essentials'
url: https://winter.group.shef.ac.uk/webelements/tantalum/
year: 2024
kind: database
license: WebElements (University of Sheffield), free online reference
nasa-europa-clipper:
title: Placing the Europa Clipper vault plate
url: https://science.nasa.gov/missions/europa-clipper/placing-the-europa-clipper-vault-plate
year: 2024
kind: web
license: public domain (NASA)
passive-components-tantalum:
title: 'Tantalum Supply Routes for Mil-Spec Capacitors: From Ore, to Powder, to Part'
url: https://passive-components.eu/tantalum-supply-routes-for-mil-spec-capacitors-from-ore-to-powder-to-part
year: 2020
kind: web
license: Industry trade article, all rights reserved
pubchem-tantalum:
title: 'Tantalum (CID 23956): safety and hazards, GHS classification'
url: https://pubchem.ncbi.nlm.nih.gov/compound/Tantalum
year: 2026
kind: database
license: PubChem, public domain
wikipedia-tantalum:
title: Tantalum
url: https://en.wikipedia.org/wiki/Tantalum
year: 2026
kind: web
license: CC BY-SA 4.0
usgs-mcs-2026-tantalum:
title: 'Mineral Commodity Summaries 2026: Tantalum'
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
year: 2026
kind: report
license: US government work, public domain
nist-xray-z73:
title: 'X-Ray Mass Attenuation Coefficients: Tantalum (Z = 73)'
url: https://physics.nist.gov/PhysRefData/XrayMassCoef/ElemTab/z73.html
year: 2026
kind: database
license: NIST, public domain
nist-xray-z13:
title: 'X-Ray Mass Attenuation Coefficients: Aluminum (Z = 13)'
url: https://physics.nist.gov/PhysRefData/XrayMassCoef/ElemTab/z13.html
year: 2026
kind: database
license: NIST, public domain
samaterials-tantalum-corrosion:
title: Corrosion resistance of tantalum to water, aqueous solutions and non-metals
url: https://samaterials.com/content/corrosion-resistance-of-tantalum-to-water-aqueous-solutions-and-non-metals.html
year: 2026
kind: web
license: Vendor web page, all rights reserved
license: CC-BY-4.0
status: draft
author: assistant
story:
risk_groups:
- title: For people
lead: This profile has no sourced health data for tantalum metal.
level: 1
verdict: Not assessed in this run
points:
- label: Metal in use
line: Tantalum metal is used as a sealed shield and inside capacitors. No hazard classification was read in this run, so none is stated here.
- title: If it fails
lead: No sourced failure mode was found in this run.
level: 1
verdict: Not assessed
points:
- label: Mechanical
line: The sheet is a local shield. Its density is 16650 kg/m3, and its Vickers hardness is 873 MN/m2.
why: Tantalum is dense and melts at 3017 degC, so a thin sheet can block radiation locally without a heavy enclosure. The NASA Europa Clipper vault plate is the sourced example of it on a spacecraft.
can_do:
- label: Give a dense,
value: ''
line: Give a dense, high-melting shield in thin sheet on a spacecraft.
- label: Serve as the
value: ''
line: Serve as the anode material of capacitors, which take the largest share of tantalum demand.
compare: Tantalum is 16650 kg/m3 and melts at 3017 degC; aluminium, the usual spacecraft shield metal, is far lighter and melts much lower. Its photon mass attenuation is 4.302 cm2/g at 0.1 MeV, against 0.170 cm2/g for aluminium, and 0.06567 cm2/g against 0.06146 cm2/g at 1 MeV (NIST, per gram). Per gram the two are close at 1 MeV, so tantalum wins mainly on density for a thin plate.
compare_rows:
- scope: material
label: Density
benchmark: density
- scope: material
label: Melting point
benchmark: melting_point
- scope: material
label: Thermal conductivity
benchmark: thermal_conductivity
handling:
- Keep away from heat, sparks and open flames, and ground equipment when handling powder or swarf (PubChem P210, P240, P241).
- Wear protective gloves and avoid breathing dust (PubChem P280, H335).
- Keep away from hydrofluoric acid and hot alkaline solutions (corrosion section).
good_for:
- Local radiation spot shields around sensitive electronics.
watch_out:
- Its mass is high for large areas.
- Hydrofluoric acid and hydrogen uptake in hot acids limit its use in chemical service.
- The NIST values are per gram of material; no dose reduction in a spacecraft vault was sourced in this run.
verdict: Tantalum is a dense, high-melting metal used as local spot shielding and as capacitor anode material. This deepened draft adds recipe, supply shares from the USGS 2026 summary, corrosion, hazards from PubChem, and NIST photon attenuation against aluminium.
recipe:
line: Tantalum is the element Ta, atomic number 73, a single-element metal with no alloying in pure form. Its ore is mainly tantalite, (Fe,Mn)Ta2O6, usually mined with columbite, the niobium ore. Ore is concentrated by gravity separation, leached with hydrofluoric acid and sulfuric or hydrochloric acid, and purified by solvent extraction into an organic solvent. Niobium is removed by lowering the acid ionic strength, and the tantalum is then precipitated with ammonia and calcined to Ta2O5. The metal is made by reducing the purified salt or oxide; The first metal was made by reducing tantalum chloride in hydrogen, as de Marignac did in the 19th century. The metal powder is pressed into pellets for capacitors.
parts:
- name: Tantalum
symbol: Ta
atoms: 1
atomic_weight: 180.94788
role: The whole material. WebElements prints the relative atomic mass as 180.94788 (2). Natural tantalum is almost entirely one isotope, with a very small share of a metastable isomer (Wikipedia).
checked_values: 19
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.
| # | Source | Type | Year | Used for |
|---|---|---|---|---|
| Tantalum - 73Ta: physical properties | database | 2024 | 11 values | |
| Tantalum - 73Ta: the essentials | database | 2024 | 3 values | |
| Placing the Europa Clipper vault plate | web | 2024 | 1 value | |
| Tantalum Supply Routes for Mil-Spec Capacitors: From Ore, to Powder, to Part | web | 2020 | 2 values | |
| Tantalum (CID 23956): safety and hazards, GHS classification | database | 2026 | 6 values | |
| Tantalum | web | 2026 | 2 values | |
| Mineral Commodity Summaries 2026: Tantalum | report | 2026 | 1 value | |
| X-Ray Mass Attenuation Coefficients: Tantalum (Z = 73) | database | 2026 | 4 values | |
| X-Ray Mass Attenuation Coefficients: Aluminum (Z = 13) | database | 2026 | 3 values | |
| Corrosion resistance of tantalum to water, aqueous solutions and non-metals | web | 2026 | 5 values |