Transition-metal silicides (disilicides) MSi2
MSi2, with M = W, Ti, Ta, Cr, Nb or Fe
Transition-metal disilicides share the formula MSi2.
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.
Melt
2160 degC
Low resistivity
12 to 24 uOhm·cm
Density
9.3 g/cm3
Recipe, share of the weight
- Si 8.4%Silicon
- W 27.5%Tungsten
- Ti 7.1%Titanium
- Ta 27.0%Tantalum
- Cr 7.8%Chromium
- Nb 13.9%Niobium
- Fe 8.3%Iron
Best for
Low-resistivity silicide contacts in microelectronics (TiSi2 C54, WSi2) and high-melting silicide coatings
Weakest at
Oxidation at intermediate temperatures for NbSi2 and CrSi2, and no flight or space data for any of the six compounds
Risk at a glance
- People None found. Irritant reports for CrSi2 and FeSi2
- If it fails Moderate. Accelerated oxidation and porous scale on NbSi2 coatings above 1073 K
- Corrosion Moderate. NbSi2 oxidises fast above 1073 K in air because its oxide scale becomes porous.
Quick facts: MSi2
| Property | Value | Basis |
|---|---|---|
| Density | 4.13 to 9.3 g/cm³ | 4 sourced values across conditions |
| Melting point | 1,490 to 2,200 °C | 5 sourced values across conditions |
| Electrical resistivity | 1.2e-7 to 5.0e-7 Ω·m | 2 sourced values across conditions |
What is the density of Transition-metal silicides (disilicides) (MSi2)?
Transition-metal silicides (disilicides) (MSi2) has a density of 4.13 to 9.3 g/cm³. The range covers 4 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is the melting point of Transition-metal silicides (disilicides) (MSi2)?
Transition-metal silicides (disilicides) (MSi2) has a melting point of 1,490 to 2,200 °C. The range covers 5 sourced values across the tempers, forms and test conditions the sources report; room-temperature values are used where a source states a temperature.
What is Transition-metal silicides (disilicides) (MSi2) used for?
Uses recorded in the sources include Silicide contacts and gate electrodes in integrated circuits (TiSi2, C54 phase); Contact material and polysilicon shunt in microelectronics (WSi2); Semiconductor metallization (TaSi2 sputtering targets).
Why it exists
Transition-metal disilicides combine a high melting point with low electrical resistivity. TiSi2 in the C54 phase and WSi2 are used as contacts and gate silicides in integrated circuits. TaSi2 is used in semiconductor metallization. NbSi2 is studied as an oxidation-resistant coating for niobium alloys, but it oxidises fast above 1073 K. beta-FeSi2 is a semiconductor with an indirect gap of 0.73 to 0.78 eV, studied for thermoelectric use. The sources read here give melting points of 1490 to 2200 degC for four of the compounds, and no flight or space data.
Where it's used
Microelectronics contacts
TiSi2 is commonly applied as interconnects and gate electrodes in integrated circuits. WSi2 is mostly used as a contact material and as a shunt over polysilicon lines, according to the supplier. TaSi2 is used in semiconductor metallization.
Oxidation-protective coating (research)
NbSi2 is described as a promising coating for niobium-base alloys. Its oxidation is complicated and depends on temperature, so it is a research candidate, not a production coating.
Thermoelectric research
beta-FeSi2 is studied as a sustainable thermoelectric material because it is abundant and non-toxic.
Space applications
No flight, space or lunar source for any of the six compounds was read in this run.
Recipe
MSi2, with M = W, Ti, Ta, Cr, Nb or Fe
Each compound is a 1:2 metal-to-silicon phase. Per formula unit: one transition-metal atom and two silicon atoms (WSi2, TiSi2, TaSi2, CrSi2, NbSi2 or FeSi2). The metal parts below are one per compound, not a single mixture.
| Ingredient | Atoms per unit | Share of the weight | What it does |
|---|---|---|---|
| Silicon Si | 2 | 8.4% | Two per formula unit. Silicon forms the disilicide lattice with the metal and, in microelectronics contacts, bonds to the silicon substrate. |
| Tungsten W | 1 | 27.5% | The metal in WSi2, which is used for microelectronics contacts and has a melting point of 2160 degC. |
| Titanium Ti | 1 | 7.1% | The metal in TiSi2. The low-resistivity C54 phase is the one used for contacts. |
| Tantalum Ta | 1 | 27.0% | The metal in TaSi2, used in semiconductor metallization. |
| Chromium Cr | 1 | 7.8% | The metal in CrSi2. |
| Niobium Nb | 1 | 13.9% | The metal in NbSi2, studied as an oxidation-resistant coating for niobium alloys. |
| Iron Fe | 1 | 8.3% | The metal in beta-FeSi2, a semiconductor studied for thermoelectric use. |
Weight shares are calculated from standard atomic weights.
What it can do
Melt
2160 degC
measured
WSi2 melts at 2160 degC according to its supplier, and TaSi2 at 2200 degC. CrSi2 melts at 1490 degC and NbSi2 at 1950 degC.
Low resistivity
12 to 24 uOhm·cm
measured
The C54 TiSi2 thin film has a resistivity of 12 to 24 uOhm·cm. TaSi2 bulk is quoted at 35 to 50 uOhm·cm by a supplier.
Density
9.3 g/cm3
measured
WSi2 powder has a density of 9.3 g/cm3 and TaSi2 has 9.14 g/cm3. CrSi2 has 4.91 g/cm3 and C54 TiSi2 about 4.13 g/cm3 (supplier, approximate).
How it compares
The compounds split into two groups by density and melting point. WSi2 and TaSi2 are dense (9.3 and 9.14 g/cm3) and melt above 2160 degC. CrSi2 and TiSi2 are lighter and melt near 1500 degC. For microelectronics contacts, the TiSi2 C54 phase has the lowest resistivity quoted here (12 to 24 uOhm·cm, thin film), while TaSi2 bulk is quoted at 35 to 50 uOhm·cm.
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. Other materials are shown beside it; each was measured under its own conditions, so open its page before comparing closely. Compare every grade in the family.
| Measurement | MSi2 | CrB2 | LaB6 | TM borides | MoSi2 | TiB2 |
|---|---|---|---|---|---|---|
| Thermal behavior and safety | ||||||
| Melting point, WSi2 powderMelting Point field of the supplier product page | 2160 °C | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C |
| Melting point, C54 TiSi2 (supplier approximate) | 1500 °C3 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C |
| Melting point, TaSi2 (Micron Metals) | 2200 °C4 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C |
| Melting point, CrSi2 (Micron Metals) | 1490 °C6 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C |
| Melting point, NbSi2 (Micron Metals) | 1950 °C8 | 1850 °C | 2528 K | 3245 °C | no data | 3225 °C |
| Physical and electrical | ||||||
| Density, WSi2 powderDensity field of the supplier product page | 9.3 g/cm³ | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ |
| Electrical resistivity, C54 TiSi2 thin film | 12 to 24 uOhm·cm1 | no data | 15 uOhm·cm | no data | 23 to 27 uOhm·cm | 9 to 15 uOhm·cm |
| Density, C54 TiSi2 (supplier theoretical) | 4.13 g/cm³2 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ |
| Density, TaSi2 (theoretical, Micron Metals)Density field of the Micron Metals product page | 9.14 g/cm³ | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ |
| Electrical resistivity, TaSi2 (supplier bulk figure) | 35 to 50 uOhm·cm5 | no data | 15 uOhm·cm | no data | 23 to 27 uOhm·cm | 9 to 15 uOhm·cm |
| Density, CrSi2 (supplier evaporation material) | 4.91 g/cm³7 | 5.15 g/cc | 4.72 g/cm³ | 6.119 g/cm³ | 5.6 g/cm³ | 4.5 g/cm³ |
| Other measurements | ||||||
| Indirect band gap, beta-FeSi2 (values quoted in the arXiv paper) | 0.73 to 0.78 eV9 | no data | no data | no data | no data | no data |
Why choose it, and why not
Good for
- Silicide contacts in integrated circuits. TiSi2 C54 thin film is quoted at 12 to 24 uOhm·cm, and WSi2 is used as a contact material.
- High-melting silicide powders. WSi2 melts at 2160 degC and TaSi2 at 2200 degC according to the suppliers.
Watch out for
- NbSi2 oxidation: accelerated above 1073 K, with a porous oxide layer.
- Density and melting point differ between suppliers. Use the supplier certificate for the grade you buy.
- No space, radiation or vacuum data for any of the six compounds.
The six disilicides are useful as contacts and high-melting powders. Only TiSi2 and WSi2 have a clear microelectronics use in the sources read, and NbSi2 coatings do not yet hold up above about 1073 K.
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 | Electrical resistivity, C54 TiSi2 thin film | Resistivity row of Table 150a, column C54, copied as printed | phase C54 (low-resistivity orthorhombic phase)form thin filmprinted 12-24 (μΩ − cm) | — |
| 2 | Density, C54 TiSi2 (supplier theoretical) | Density field of the sputtering target page, printed with a tilde (approximate) | phase C54basis theoretical value printed by the supplier | Supplier figure printed as approximate (~4.13 g/cm3). Not a measured bulk density. |
| 3 | Melting point, C54 TiSi2 (supplier approximate) | Melting Point field of the sputtering target page, printed as approximately 1500 degC | phase C54basis approximate value printed by the supplier | Supplier figure printed as approximate. The Table 150a melting row in the globalsino page is not used because its column layout could not be confirmed. |
| 4 | Melting point, TaSi2 (Micron Metals) | Melting Point field of the Micron Metals product page | form powderprinted 2200°C / 3992°F | — |
| 5 | Electrical resistivity, TaSi2 (supplier bulk figure) | Electrical Resistivity (Bulk) field of the sputtering target page | basis bulk figure printed by the supplier; the page notes that film values depend on deposition and annealingphase hexagonal C40 | Supplier range, printed as approximately 35 to 50 uOhm·cm. Not a measured value for a stated test method. |
| 6 | Melting point, CrSi2 (Micron Metals) | Melting Point field of the Micron Metals CrSi2 product page | form powderprinted 1490°C / 2714°F | — |
| 7 | Density, CrSi2 (supplier evaporation material) | Density field of the supplier evaporation-materials page | form evaporation materialgrade CrSi2 | Micron Metals prints 5.5 for CrSi2 with no unit, which is not used (see gaps). |
| 8 | Melting point, NbSi2 (Micron Metals) | Melting Point field of the Micron Metals NbSi2 product page | form powderprinted 1950°C / 3542°F | — |
| 9 | Indirect band gap, beta-FeSi2 (values quoted in the arXiv paper) | Quoted in the discussion of experimental band-gap results | phase beta-FeSi2transition indirectbasis two experimental values quoted by the paper from earlier work (Filonov et al. optical absorption; Radermacher et al. photothermal deflection) | Custom property name, not in spores/property-canon.yaml. Values are quoted from earlier work, not measured in this run. |
Corrosion and compatibility
What happens when it meets other materials and environments.
| Environment | Concern | What happens |
|---|---|---|
| Air at high temperature (protective silica scale) | low | WSi2 is described by its supplier as having good oxidation resistance.1 |
| Air at 773 to 1673 K (sintered NbSi2) | moderate | NbSi2 oxidises fast above 1073 K in air because its oxide scale becomes porous.2 |
| Air, mixed-oxidation behaviour of CrSi2 | not rated | Supplier notes oxidation resistance for CrSi2 but gives no rate or limit.3 |
| # | Environment | Details | Test conditions |
|---|---|---|---|
| 1 | Air at high temperature (protective silica scale) | The supplier describes WSi2 powder as a conductive ceramic with a high melting point and good oxidation resistance. No rate or temperature limit is printed on the page read. | atmosphere airtemperature not stated |
| 2 | Air at 773 to 1673 K (sintered NbSi2) | The study oxidised sintered NbSi2 in air from 773 to 1673 K and reports accelerated oxidation at 1073 K and above. The accelerated oxidation was attributed to a porous oxide layer. The authors describe the oxidation behaviour as complicated and dependent on temperature, and call NbSi2 a promising candidate for coating Nb-base alloys. | atmosphere airtemperature 773 to 1673 K (sintered NbSi2) |
| 3 | Air, mixed-oxidation behaviour of CrSi2 | Micron Metals lists oxidation resistance among the properties of CrSi2 powder, but the page read gives no oxidation rate, temperature limit or scale description, so no rating beyond a supplier note is recorded. | atmosphere airtemperature not stated |
Risks and side effects
Hazards to people, what happens when a cell overheats, and how the material is handled and stored.
For people
PubChem's aggregated GHS data for CrSi2 and beta-FeSi2 give skin and eye irritation codes. The WSi2 record has no classification. No supplier safety data sheet for these powders was read in this run.
- Powder
- CrSi2 is reported with H302, H312 and H332 (harmful if swallowed, in contact with skin or if inhaled) for part of its reports, and with H315, H317 and H319 for most of them.
- Eyes and skin
- beta-FeSi2 and NbSi2 are reported with H315 or H319 (skin or serious eye irritation).
If a coating or element fails
These points come from the NbSi2 oxidation study and the sources on use.
- Accelerated oxidation
- NbSi2 oxidised fast above 1073 K in air, because the oxide scale became porous. A coating in that range would not protect the niobium alloy.
- Contacts
- TiSi2 and WSi2 contacts depend on low resistivity; the TiSi2 C54 thin film is quoted at 12 to 24 uOhm·cm.
Handling
- Dust
- Avoid breathing and handling the powder, as PubChem's irritation codes for CrSi2 and beta-FeSi2 suggest.
Test details
The original wording and numbers from the sources, for readers who want them.
Failure risks
| Failure | Trigger and consequence |
|---|---|
| Accelerated oxidation and porous scale on NbSi2 coatings above 1073 Kmoderate severity | Sustained exposure to air at 1073 K and aboveThe porous oxide layer does not protect the substrate, so the coating loses its oxidation barrier. The authors report the cause as a porous oxide layer formed during accelerated oxidation. |
Handling and storage
- PubChem reports H315, H317 and H319 for CrSi2 and H315 and H319 for beta-FeSi2 (skin and eye irritation), so avoid skin and eye contact and avoid breathing dust.
Supply and geography
How common the raw materials are and where they come from.
Tungsten (WSi2)
USGS: world mine production of tungsten in 2025 was 85,000 t (rounded), with China reserves of 2,500,000 t.
- Top producers (2025)
- China 78.8%, Vietnam 3.5%, Kazakhstan 2.8%, Russia 2.4%, Bolivia 2%
Titanium (TiSi2, sponge metal)
USGS: sponge production table, 2025 estimate, world total printed as 370,000 (rounded). The United States did not produce titanium sponge in 2025.
- Top producers (2025)
- China 70.3%, Japan 14.3%, Russia 6.8%, Kazakhstan 4.3%, Saudi Arabia 3.2%
- Substitutes
- USGS: few materials have titanium metal's strength-to-weight ratio and corrosion resistance; in high-strength applications it competes with aluminum, composites, intermetallics, steel and superalloys.
Chromium (CrSi2)
USGS: mine production table, 2025 estimate, world total printed as 51,000 (rounded).
- Top producers (2025)
- South Africa 45.1%, Turkey 17.6%, Kazakhstan 13.7%, India 5.9%, Brazil 3.9%
Niobium (NbSi2)
USGS: world mine production of niobium 2025 estimate printed as 112,000 (rounded); reserves printed as more than 21,000,000.
- Top producers (2025)
- Brazil 92.9%, Canada 5.4%, Russia 0.3%
Tantalum (TaSi2)
USGS: world mine production of tantalum 2025 estimate printed as 2,500 (rounded).
- Top producers (2025)
- Congo (Kinshasa) 52%, Rwanda 16%, Nigeria 15.6%, China 3.2%
Documents
Datasheets, safety data sheets, papers and standards you can open.
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: transition-metal-silicides
spore_version: 0.2
family: carbide-nitride-boride-ceramics
name: Transition-metal silicides (disilicides)
abbreviation: MSi2
role: microelectronics contact silicides and oxidation-resistant silicide coatings (WSi2, TiSi2, TaSi2, CrSi2, NbSi2, FeSi2)
category: ceramics
type: ultra-high-temperature-ceramics
summary: |
Transition-metal disilicides share the formula MSi2. The sources read here cover six of them. WSi2 has a density of 9.3 g/cm3 and a melting point of 2160 degC (Stanford Advanced Materials). TiSi2 in the low-resistivity C54 phase has a thin-film resistivity of 12 to 24 uOhm·cm and is used as an interconnect and gate silicide in integrated circuits. TaSi2 melts at 2200 degC with a density of 9.14 g/cm3 (Micron Metals). CrSi2 melts at 1490 degC and NbSi2 at 1950 degC. Beta-FeSi2 is a semiconductor with a quoted indirect gap of 0.73 to 0.78 eV, studied as a thermoelectric. NbSi2 is studied as an oxidation-resistant coating for niobium alloys, but a Hokkaido University study reports accelerated oxidation above 1073 K in air.
best_for: Low-resistivity silicide contacts in microelectronics (TiSi2 C54, WSi2) and high-melting silicide coatings
weakest_at: Oxidation at intermediate temperatures for NbSi2 and CrSi2, and no flight or space data for any of the six compounds
identity:
formula: MSi2, with M = W, Ti, Ta, Cr, Nb or Fe
source: pubchem-wsi2
where: PubChem compound records CID 9794752 (WSi2), 6336889 (TiSi2), 6336888 (TaSi2), 13710602 (CrSi2), 6336884 (NbSi2) and 6336880 (FeSi2); MolecularFormula property of each
tags:
environments: []
stresses:
- extreme-heat
applications:
- electronics-and-chips
- structures
- thermal-control
properties:
- benchmark: density
label: Density, WSi2 powder
value: 9.3
unit: g/cm3
scope: material
conditions:
form: powder
grade: WSi2 powder, supplier listing
method: Density field of the supplier product page
status: ground
source: samaterials-wsi2
where: Product specification block, Density field
- benchmark: melting_point
label: Melting point, WSi2 powder
value: 2160
unit: degC
scope: material
conditions:
form: powder
printed: 3,920°F (2,160°C)
method: Melting Point field of the supplier product page
status: ground
source: samaterials-wsi2
where: Product specification block, Melting Point field
- benchmark: electrical_resistivity
label: Electrical resistivity, C54 TiSi2 thin film
value: 12
value_high: 24
bound: range
unit: uOhm·cm
scope: material
conditions:
phase: C54 (low-resistivity orthorhombic phase)
form: thin film
printed: 12-24 (μΩ − cm)
method: Resistivity row of Table 150a, column C54, copied as printed
status: ground
source: globalsino-tisi2
where: Table 150a, Properties of TiSi2 materials, resistivity row, C54 column
- benchmark: density
label: Density, C54 TiSi2 (supplier theoretical)
value: 4.13
unit: g/cm3
scope: material
conditions:
phase: C54
basis: theoretical value printed by the supplier
method: Density field of the sputtering target page, printed with a tilde (approximate)
status: ground
note: Supplier figure printed as approximate (~4.13 g/cm3). Not a measured bulk density.
source: sputtertargets-tisi2
where: Specification table, Density field
- benchmark: melting_point
label: Melting point, C54 TiSi2 (supplier approximate)
value: 1500
unit: degC
scope: material
conditions:
phase: C54
basis: approximate value printed by the supplier
method: Melting Point field of the sputtering target page, printed as approximately 1500 degC
status: ground
note: Supplier figure printed as approximate. The Table 150a melting row in the globalsino page is not used because its column layout could not be confirmed.
source: sputtertargets-tisi2
where: Specification table, Melting Point field
- benchmark: density
label: Density, TaSi2 (theoretical, Micron Metals)
value: 9.14
unit: g/cm3
scope: material
conditions:
form: powder
grade: TaSi2 powder
method: Density field of the Micron Metals product page
status: ground
source: micronmetals-tasi2
where: Product specification table, Density field
- benchmark: melting_point
label: Melting point, TaSi2 (Micron Metals)
value: 2200
unit: degC
scope: material
conditions:
form: powder
printed: 2200°C / 3992°F
method: Melting Point field of the Micron Metals product page
status: ground
source: micronmetals-tasi2
where: Product specification table, Melting Point field
- benchmark: electrical_resistivity
label: Electrical resistivity, TaSi2 (supplier bulk figure)
value: 35
value_high: 50
bound: range
unit: uOhm·cm
scope: material
conditions:
basis: bulk figure printed by the supplier; the page notes that film values depend on deposition and annealing
phase: hexagonal C40
method: Electrical Resistivity (Bulk) field of the sputtering target page
status: ground
note: Supplier range, printed as approximately 35 to 50 uOhm·cm. Not a measured value for a stated test method.
source: sputtertargets-tasi2
where: Specification table, Electrical Resistivity (Bulk) field
- benchmark: melting_point
label: Melting point, CrSi2 (Micron Metals)
value: 1490
unit: degC
scope: material
conditions:
form: powder
printed: 1490°C / 2714°F
method: Melting Point field of the Micron Metals CrSi2 product page
status: ground
source: micronmetals-crsi2
where: Product specification table, Melting Point field
- benchmark: density
label: Density, CrSi2 (supplier evaporation material)
value: 4.91
unit: g/cm3
scope: material
conditions:
form: evaporation material
grade: CrSi2
method: Density field of the supplier evaporation-materials page
status: ground
note: Micron Metals prints 5.5 for CrSi2 with no unit, which is not used (see gaps).
source: sputtertargets-crsi2
where: Specification table, Density field
- benchmark: melting_point
label: Melting point, NbSi2 (Micron Metals)
value: 1950
unit: degC
scope: material
conditions:
form: powder
printed: 1950°C / 3542°F
method: Melting Point field of the Micron Metals NbSi2 product page
status: ground
source: micronmetals-nbsi2
where: Product specification table, Melting Point field
- benchmark: band_gap
label: Indirect band gap, beta-FeSi2 (values quoted in the arXiv paper)
value: 0.73
value_high: 0.78
bound: range
unit: eV
scope: material
conditions:
phase: beta-FeSi2
transition: indirect
basis: two experimental values quoted by the paper from earlier work (Filonov et al. optical absorption; Radermacher et al. photothermal deflection)
method: Quoted in the discussion of experimental band-gap results
status: ground
note: Custom property name, not in spores/property-canon.yaml. Values are quoted from earlier work, not measured in this run.
source: arxiv-fesi2
where: Section on experimental band gap of beta-FeSi2, paragraph beginning "Experimental results on the band gap"
corrosion:
- environment: Air at high temperature (protective silica scale)
headline: WSi2 is described by its supplier as having good oxidation resistance.
effect: The supplier describes WSi2 powder as a conductive ceramic with a high melting point and good oxidation resistance. No rate or temperature limit is printed on the page read.
rating: low
conditions:
atmosphere: air
temperature: not stated
source: samaterials-wsi2
where: Product description paragraph
- environment: Air at 773 to 1673 K (sintered NbSi2)
headline: NbSi2 oxidises fast above 1073 K in air because its oxide scale becomes porous.
effect: The study oxidised sintered NbSi2 in air from 773 to 1673 K and reports accelerated oxidation at 1073 K and above. The accelerated oxidation was attributed to a porous oxide layer. The authors describe the oxidation behaviour as complicated and dependent on temperature, and call NbSi2 a promising candidate for coating Nb-base alloys.
rating: moderate
conditions:
atmosphere: air
temperature: 773 to 1673 K (sintered NbSi2)
source: hokudai-nbsi2
where: Abstract, first paragraph
- environment: Air, mixed-oxidation behaviour of CrSi2
headline: Supplier notes oxidation resistance for CrSi2 but gives no rate or limit.
effect: Micron Metals lists oxidation resistance among the properties of CrSi2 powder, but the page read gives no oxidation rate, temperature limit or scale description, so no rating beyond a supplier note is recorded.
rating: unknown
conditions:
atmosphere: air
temperature: not stated
source: micronmetals-crsi2
where: Product description
risks:
hazards:
- text: PubChem lists WSi2 as not classified under GHS for 100% (3 of 3) of the reports it holds, so no hazard label is recorded for WSi2 in that record.
ghs: []
source: pubchem-wsi2
where: Safety and Hazards, GHS Classification (CID 9794752)
- text: 'PubChem aggregated GHS for CrSi2 (CID 13710602): H302, H312 and H332 (18.1 percent of reports each), H315 and H319 (79.6 percent each), H317 (20.4 percent). Signal word Warning.'
ghs:
- H302
- H312
- H315
- H317
- H319
- H332
source: pubchem-crsi2
where: Safety and Hazards, GHS Classification (CID 13710602)
- text: 'PubChem aggregated GHS for beta-FeSi2 (CID 6336880): H315 and H319 (66.7 percent of reports each). Signal word Warning.'
ghs:
- H315
- H319
source: pubchem-fesi2
where: Safety and Hazards, GHS Classification (CID 6336880)
- text: 'PubChem aggregated GHS for NbSi2 (CID 6336884): H319 (100 percent of the reports it holds). Signal word Warning.'
ghs:
- H319
source: pubchem-nbsi2
where: Safety and Hazards, GHS Classification (CID 6336884)
failure_risks:
- mode: Accelerated oxidation and porous scale on NbSi2 coatings above 1073 K
trigger: Sustained exposure to air at 1073 K and above
consequence: The porous oxide layer does not protect the substrate, so the coating loses its oxidation barrier. The authors report the cause as a porous oxide layer formed during accelerated oxidation.
severity: moderate
source: hokudai-nbsi2
where: Abstract, first paragraph
side_effects: []
handling:
- text: PubChem reports H315, H317 and H319 for CrSi2 and H315 and H319 for beta-FeSi2 (skin and eye irritation), so avoid skin and eye contact and avoid breathing dust.
source: pubchem-crsi2
where: Safety and Hazards, GHS Classification (CID 13710602)
mitigations: []
uses:
- application: electronics-and-chips
device: Silicide contacts and gate electrodes in integrated circuits (TiSi2, C54 phase)
example: TiSi2 is commonly applied as interconnects in ultra-large-scale integrated circuits and as gate electrodes in MOS transistors, because it has low resistivity and good electrical contact with silicon.
source: globalsino-tisi2
where: Introduction paragraph of the TiSi2 entry, before Table 150a
- application: electronics-and-chips
device: Contact material and polysilicon shunt in microelectronics (WSi2)
example: The supplier says WSi2 is mostly used in microelectronics as a contact material because of its small resistance, and as a shunt over polysilicon lines to raise conductivity and signal speed.
source: samaterials-wsi2
where: Product description paragraph
- application: electronics-and-chips
device: Semiconductor metallization (TaSi2 sputtering targets)
example: The supplier describes TaSi2 as a critical material in semiconductor metallization, with a hexagonal C40 structure that is the stable low-resistivity phase for thin films.
source: sputtertargets-tasi2
where: Product description and phase table
- application: structures
device: Oxidation-protective silicide coating on niobium-base alloys (research)
example: The Hokkaido study calls NbSi2 a promising candidate as a coating material for Nb-base alloys, but reports complicated oxidation behaviour that depends on temperature. This is a research finding, not a flight use.
source: hokudai-nbsi2
where: Abstract, first sentence
- application: thermal-control
device: Beta-FeSi2 thermoelectric material for waste-heat conversion (research)
example: A review describes beta-FeSi2 as a sustainable thermoelectric material because it is abundant, non-toxic and environmentally compatible.
source: pmc-fesi2-review
where: Abstract, first sentence
supply:
- subject: Tungsten (WSi2)
abundance: 'USGS: world mine production of tungsten in 2025 was 85,000 t (rounded), with China reserves of 2,500,000 t.'
producers:
- country: China
share_percent: 78.8
year: 2025
- country: Vietnam
share_percent: 3.5
year: 2025
- country: Kazakhstan
share_percent: 2.8
year: 2025
- country: Russia
share_percent: 2.4
year: 2025
- country: Bolivia
share_percent: 2
year: 2025
substitutes: []
source: usgs-mcs2026-tungsten
where: World Mine Production and Reserves table, 2025 column (world total 85,000 rounded; shares calculated by Space Mushroom against that total)
- subject: Titanium (TiSi2, sponge metal)
abundance: 'USGS: sponge production table, 2025 estimate, world total printed as 370,000 (rounded). The United States did not produce titanium sponge in 2025.'
producers:
- country: China
share_percent: 70.3
year: 2025
- country: Japan
share_percent: 14.3
year: 2025
- country: Russia
share_percent: 6.8
year: 2025
- country: Kazakhstan
share_percent: 4.3
year: 2025
- country: Saudi Arabia
share_percent: 3.2
year: 2025
substitutes:
- 'USGS: few materials have titanium metal''s strength-to-weight ratio and corrosion resistance; in high-strength applications it competes with aluminum, composites, intermetallics, steel and superalloys.'
source: usgs-mcs2026-titanium
where: Sponge production table, 2025 estimate column (shares calculated by Space Mushroom against the 370,000 world total); Domestic Production and Use; Substitutes
- subject: Chromium (CrSi2)
abundance: 'USGS: mine production table, 2025 estimate, world total printed as 51,000 (rounded).'
producers:
- country: South Africa
share_percent: 45.1
year: 2025
- country: Turkey
share_percent: 17.6
year: 2025
- country: Kazakhstan
share_percent: 13.7
year: 2025
- country: India
share_percent: 5.9
year: 2025
- country: Brazil
share_percent: 3.9
year: 2025
source: usgs-mcs2026-chromium
where: Mine production table, 2025e column (world total 51,000 rounded; shares calculated by Space Mushroom against that total)
- subject: Niobium (NbSi2)
abundance: 'USGS: world mine production of niobium 2025 estimate printed as 112,000 (rounded); reserves printed as more than 21,000,000.'
producers:
- country: Brazil
share_percent: 92.9
year: 2025
- country: Canada
share_percent: 5.4
year: 2025
- country: Russia
share_percent: 0.3
year: 2025
source: usgs-mcs2026-niobium
where: Mine production table, 2025e column (world total 112,000 rounded; shares calculated by Space Mushroom against that total)
- subject: Tantalum (TaSi2)
abundance: 'USGS: world mine production of tantalum 2025 estimate printed as 2,500 (rounded).'
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
source: usgs-mcs2026-tantalum
where: Mine production table, 2025e column (world total 2,500 rounded; shares calculated by Space Mushroom against that total)
media: []
documents:
- title: Stanford Advanced Materials, tungsten disilicide (WSi2) powder product page
type: datasheet
url: https://www.samaterials.com/tungsten/1475-tungsten-disilicide-wsi2-powder.html
year: 2026
- title: Micron Metals, tantalum disilicide powder product page
type: datasheet
url: https://micronmetals.com/product/tantalum-disilicide-powder
year: 2026
- title: Micron Metals, chromium disilicide powder product page
type: datasheet
url: https://micronmetals.com/product/chromium-disilicide-powder/
year: 2026
- title: Micron Metals, niobium disilicide powder product page
type: datasheet
url: https://micronmetals.com/product/niobium-disilicide-powder/
year: 2026
- title: Hokkaido University, Improvement of Oxidation Resistance of NbSi2 by Addition of Boron (Materials Science Forum 502)
type: paper
url: https://eprints.lib.hokudai.ac.jp/repo/huscap/all/733/NbSi2.pdf
- title: PubChem compound records for the six disilicides (GHS classification)
type: database
url: https://pubchem.ncbi.nlm.nih.gov/compound/9794752
year: 2026
- title: USGS Mineral Commodity Summaries 2026, Tungsten
type: report
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
year: 2026
gaps:
- Six compounds are covered in one file, so most families have only two to four sourced properties. TaSi2, CrSi2, NbSi2 and FeSi2 have no sourced electrical-resistivity or hardness value except TaSi2 (supplier bulk range).
- No melting point for FeSi2 found. The PMC review and the arXiv paper note incongruent melting but print no temperature in the parts read.
- Density of NbSi2 and CrSi2 from Micron Metals is printed with no unit (5.6 and 5.5), so it is left out. The sputtering-target page gives 4.91 g/cm3 for CrSi2; no sourced density for NbSi2.
- Crystal structures are stated by sources (C54 for TiSi2 in the sputtering target and globalsino pages, C40 hexagonal for TaSi2 and NbSi2 and CrSi2) but are not recorded as identity fields.
- Melting point of TiSi2 C54 is a supplier approximate figure (about 1500 degC); the Table 150a melting row (1540) is not used because the column could not be matched to C54 with confidence.
- Band-gap values for FeSi2 are quoted from earlier work by the arXiv paper, not measured in this run. Direct-gap value (0.85 eV, thin film) was not read on a fetched page.
- Hazard data rest on the PubChem aggregate. No safety data sheet for any of the six compounds was read in this run; PubChem returns no GHS classification text for TiSi2 or TaSi2 in the record read.
- 'Supply: USGS critical-mineral list status for tungsten, titanium, tantalum, chromium, niobium and silicon was not read in this run, so critical_lists are left out. Silicon supply is not repeated here (see the MoSi2 profile).'
- 'Space use: no flight, radiation, vacuum or atomic-oxygen data for any of the six compounds were read in this run.'
- The NbSi2 coating research cited here is laboratory oxidation work. Coating life and pest-oxidation range are not quantified in the parts read.
- 'Custom property names used because they are not in spores/property-canon.yaml: band_gap.'
- Recipe atomic weights are for the elemental metals and silicon; PubChem compound records for the disilicides themselves give MolecularFormula, not atomic weights.
sources:
samaterials-wsi2:
title: Stanford Advanced Materials, Tungsten Disilicide Powder (WSi2) product page
url: https://www.samaterials.com/tungsten/1475-tungsten-disilicide-wsi2-powder.html
kind: datasheet
license: supplier product page, cited not reproduced
globalsino-tisi2:
title: Practical Electron Microscopy and Database, page 150 (titanium disilicide, Table 150a)
url: https://www.globalsino.com/EM/page150.html
kind: web
license: web reference, cited not reproduced
sputtertargets-tisi2:
title: Sputter Targets, Titanium Silicide (TiSi2) planar sputtering target page
url: https://www.sputtertargets.net/st11217-titanium-silicide-tisi2-planar-sputtering-target/
kind: datasheet
license: supplier product page, cited not reproduced
sputtertargets-tasi2:
title: Sputter Targets, Tantalum Silicide (TaSi2) planar target page
url: https://www.sputtertargets.net/st11216-tantalum-silicide-planar-target-tasi2-target/
kind: datasheet
license: supplier product page, cited not reproduced
sputtertargets-crsi2:
title: Sputter Targets, Chromium silicide evaporation materials page
url: https://www.sputtertargets.net/chromium-silicide-evaporation-materials.html
kind: datasheet
license: supplier product page, cited not reproduced
micronmetals-tasi2:
title: Micron Metals, Tantalum Disilicide Powder product page
url: https://micronmetals.com/product/tantalum-disilicide-powder
kind: datasheet
license: supplier product page, cited not reproduced
micronmetals-crsi2:
title: Micron Metals, Chromium Disilicide Powder product page
url: https://micronmetals.com/product/chromium-disilicide-powder/
kind: datasheet
license: supplier product page, cited not reproduced
micronmetals-nbsi2:
title: Micron Metals, Niobium Disilicide Powder product page
url: https://micronmetals.com/product/niobium-disilicide-powder/
kind: datasheet
license: supplier product page, cited not reproduced
arxiv-fesi2:
title: Thermoelectric properties of beta-FeSi2 (arXiv 1308.6529)
url: https://arxiv.org/pdf/1308.6529
kind: paper
license: arXiv, cited not reproduced
hokudai-nbsi2:
title: Kurokawa, Yamauchi, Matsushita, Improvement of Oxidation Resistance of NbSi2 by Addition of Boron, Materials Science Forum 502
url: https://eprints.lib.hokudai.ac.jp/repo/huscap/all/733/NbSi2.pdf
kind: paper
license: university repository, cited not reproduced
pmc-fesi2-review:
title: Strategies to improve the thermoelectric performance of iron silicide-based materials (PMC)
url: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12667310/
kind: paper
license: open access (PMC), cited not reproduced
pubchem-wsi2:
title: PubChem compound CID 9794752, tungsten disilicide (MolecularFormula Si2W)
url: https://pubchem.ncbi.nlm.nih.gov/compound/9794752
kind: database
license: PubChem public database
pubchem-tisi2:
title: PubChem compound CID 6336889, titanium disilicide
url: https://pubchem.ncbi.nlm.nih.gov/compound/6336889
kind: database
license: PubChem public database
pubchem-tasi2:
title: PubChem compound CID 6336888, tantalum disilicide
url: https://pubchem.ncbi.nlm.nih.gov/compound/6336888
kind: database
license: PubChem public database
pubchem-crsi2:
title: PubChem compound CID 13710602, chromium disilicide (GHS classification)
url: https://pubchem.ncbi.nlm.nih.gov/compound/13710602
kind: database
license: PubChem public database
pubchem-nbsi2:
title: PubChem compound CID 6336884, niobium disilicide (GHS classification)
url: https://pubchem.ncbi.nlm.nih.gov/compound/6336884
kind: database
license: PubChem public database
pubchem-fesi2:
title: PubChem compound CID 6336880, iron disilicide (GHS classification)
url: https://pubchem.ncbi.nlm.nih.gov/compound/6336880
kind: database
license: PubChem public database
pubchem-w:
title: PubChem compound CID 23964, tungsten (MolecularWeight 183.84)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23964
kind: database
license: PubChem public database
pubchem-ti:
title: PubChem compound CID 23963, titanium (MolecularWeight 47.867)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23963
kind: database
license: PubChem public database
pubchem-ta:
title: PubChem compound CID 23956, tantalum (MolecularWeight 180.9479)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23956
kind: database
license: PubChem public database
pubchem-cr:
title: PubChem compound CID 23976, chromium (MolecularWeight 51.996)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23976
kind: database
license: PubChem public database
pubchem-nb:
title: PubChem compound CID 23936, niobium (MolecularWeight 92.90637)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23936
kind: database
license: PubChem public database
pubchem-fe:
title: PubChem compound CID 23925, iron (MolecularWeight 55.84)
url: https://pubchem.ncbi.nlm.nih.gov/compound/23925
kind: database
license: PubChem public database
pubchem-si:
title: PubChem compound CID 5461123, silicon (MolecularWeight 28.085)
url: https://pubchem.ncbi.nlm.nih.gov/compound/5461123
kind: database
license: PubChem public database
usgs-mcs2026-tungsten:
title: Mineral Commodity Summaries 2026, Tungsten
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tungsten.pdf
kind: report
license: public domain (USGS)
usgs-mcs2026-titanium:
title: Mineral Commodity Summaries 2026, Titanium (sponge metal)
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-titanium.pdf
kind: report
license: public domain (USGS)
usgs-mcs2026-chromium:
title: Mineral Commodity Summaries 2026, Chromium
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-chromium.pdf
kind: report
license: public domain (USGS)
usgs-mcs2026-niobium:
title: Mineral Commodity Summaries 2026, Niobium
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-niobium.pdf
kind: report
license: public domain (USGS)
usgs-mcs2026-tantalum:
title: Mineral Commodity Summaries 2026, Tantalum
url: https://pubs.usgs.gov/periodicals/mcs2026/mcs2026-tantalum.pdf
kind: report
license: public domain (USGS)
license: CC-BY-4.0
updated: '2026-10-26'
review:
status: draft
method: assistant
checked_values: 12
unreachable: 3
caveats: 6
note: 'Written in this run from the Stanford Advanced Materials WSi2 page, the Globalsino TiSi2 page, three sputtering-target pages (TiSi2, TaSi2 and CrSi2), Micron Metals pages (TaSi2, CrSi2, NbSi2), the arXiv FeSi2 paper, the Hokkaido NbSi2 paper, the PMC iron silicide review, PubChem GHS records and USGS MCS 2026 tables. Not reachable or not used: the AmericanElements WSi2 page (Cloudflare block), the RSC NbSi2 paper (no text), and the Nemanich TiSi2 PDF (404).'
story:
recipe:
line: 'Each compound is a 1:2 metal-to-silicon phase. Per formula unit: one transition-metal atom and two silicon atoms (WSi2, TiSi2, TaSi2, CrSi2, NbSi2 or FeSi2). The metal parts below are one per compound, not a single mixture.'
parts:
- name: Silicon
symbol: Si
atoms: 2
atomic_weight: 28.085
role: Two per formula unit. Silicon forms the disilicide lattice with the metal and, in microelectronics contacts, bonds to the silicon substrate.
- name: Tungsten
symbol: W
atoms: 1
atomic_weight: 183.84
role: The metal in WSi2, which is used for microelectronics contacts and has a melting point of 2160 degC.
- name: Titanium
symbol: Ti
atoms: 1
atomic_weight: 47.867
role: The metal in TiSi2. The low-resistivity C54 phase is the one used for contacts.
- name: Tantalum
symbol: Ta
atoms: 1
atomic_weight: 180.9479
role: The metal in TaSi2, used in semiconductor metallization.
- name: Chromium
symbol: Cr
atoms: 1
atomic_weight: 51.996
role: The metal in CrSi2.
- name: Niobium
symbol: Nb
atoms: 1
atomic_weight: 92.90637
role: The metal in NbSi2, studied as an oxidation-resistant coating for niobium alloys.
- name: Iron
symbol: Fe
atoms: 1
atomic_weight: 55.84
role: The metal in beta-FeSi2, a semiconductor studied for thermoelectric use.
risk_groups:
- title: For people
level: 0
verdict: Irritant reports for CrSi2 and FeSi2
lead: PubChem's aggregated GHS data for CrSi2 and beta-FeSi2 give skin and eye irritation codes. The WSi2 record has no classification. No supplier safety data sheet for these powders was read in this run.
points:
- label: Powder
line: CrSi2 is reported with H302, H312 and H332 (harmful if swallowed, in contact with skin or if inhaled) for part of its reports, and with H315, H317 and H319 for most of them.
- label: Eyes and skin
line: beta-FeSi2 and NbSi2 are reported with H315 or H319 (skin or serious eye irritation).
- title: If a coating or element fails
lead: These points come from the NbSi2 oxidation study and the sources on use.
points:
- label: Accelerated oxidation
line: NbSi2 oxidised fast above 1073 K in air, because the oxide scale became porous. A coating in that range would not protect the niobium alloy.
- label: Contacts
line: TiSi2 and WSi2 contacts depend on low resistivity; the TiSi2 C54 thin film is quoted at 12 to 24 uOhm·cm.
- title: Handling
points:
- label: Dust
line: Avoid breathing and handling the powder, as PubChem's irritation codes for CrSi2 and beta-FeSi2 suggest.
why: Transition-metal disilicides combine a high melting point with low electrical resistivity. TiSi2 in the C54 phase and WSi2 are used as contacts and gate silicides in integrated circuits. TaSi2 is used in semiconductor metallization. NbSi2 is studied as an oxidation-resistant coating for niobium alloys, but it oxidises fast above 1073 K. beta-FeSi2 is a semiconductor with an indirect gap of 0.73 to 0.78 eV, studied for thermoelectric use. The sources read here give melting points of 1490 to 2200 degC for four of the compounds, and no flight or space data.
uses:
- where: Microelectronics contacts
line: TiSi2 is commonly applied as interconnects and gate electrodes in integrated circuits. WSi2 is mostly used as a contact material and as a shunt over polysilicon lines, according to the supplier. TaSi2 is used in semiconductor metallization.
- where: Oxidation-protective coating (research)
line: NbSi2 is described as a promising coating for niobium-base alloys. Its oxidation is complicated and depends on temperature, so it is a research candidate, not a production coating.
- where: Thermoelectric research
line: beta-FeSi2 is studied as a sustainable thermoelectric material because it is abundant and non-toxic.
- where: Space applications
line: No flight, space or lunar source for any of the six compounds was read in this run.
can_do:
- label: Melt
benchmark: melting_point
value: 2160 degC
line: WSi2 melts at 2160 degC according to its supplier, and TaSi2 at 2200 degC. CrSi2 melts at 1490 degC and NbSi2 at 1950 degC.
- label: Low resistivity
benchmark: electrical_resistivity
value: 12 to 24 uOhm·cm
line: The C54 TiSi2 thin film has a resistivity of 12 to 24 uOhm·cm. TaSi2 bulk is quoted at 35 to 50 uOhm·cm by a supplier.
- label: Density
benchmark: density
value: 9.3 g/cm3
line: WSi2 powder has a density of 9.3 g/cm3 and TaSi2 has 9.14 g/cm3. CrSi2 has 4.91 g/cm3 and C54 TiSi2 about 4.13 g/cm3 (supplier, approximate).
compare: The compounds split into two groups by density and melting point. WSi2 and TaSi2 are dense (9.3 and 9.14 g/cm3) and melt above 2160 degC. CrSi2 and TiSi2 are lighter and melt near 1500 degC. For microelectronics contacts, the TiSi2 C54 phase has the lowest resistivity quoted here (12 to 24 uOhm·cm, thin film), while TaSi2 bulk is quoted at 35 to 50 uOhm·cm.
compare_rows:
- label: Density
benchmark: density
- label: Melting point
benchmark: melting_point
- label: Electrical resistivity
benchmark: electrical_resistivity
handling:
- PubChem lists irritation codes for CrSi2 and beta-FeSi2. Avoid skin and eye contact and avoid breathing the dust.
- NbSi2 oxidises fast above 1073 K in air, so do not expect a coating to hold above that temperature without a protective layer.
good_for:
- Silicide contacts in integrated circuits. TiSi2 C54 thin film is quoted at 12 to 24 uOhm·cm, and WSi2 is used as a contact material.
- High-melting silicide powders. WSi2 melts at 2160 degC and TaSi2 at 2200 degC according to the suppliers.
watch_out:
- 'NbSi2 oxidation: accelerated above 1073 K, with a porous oxide layer.'
- Density and melting point differ between suppliers. Use the supplier certificate for the grade you buy.
- No space, radiation or vacuum data for any of the six compounds.
verdict: The six disilicides are useful as contacts and high-melting powders. Only TiSi2 and WSi2 have a clear microelectronics use in the sources read, and NbSi2 coatings do not yet hold up above about 1073 K.
References
Every number above carries a reference number. Click one to see the source and where in it the value comes from.