{ "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.\n", "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", "designations": [], "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, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point, WSi2 powder", "value": 2160, "bound": "exact", "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", "source_detail": { "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" } }, { "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density, C54 TiSi2 (supplier theoretical)", "value": 4.13, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point, C54 TiSi2 (supplier approximate)", "value": 1500, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density, TaSi2 (theoretical, Micron Metals)", "value": 9.14, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point, TaSi2 (Micron Metals)", "value": 2200, "bound": "exact", "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", "source_detail": { "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" } }, { "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point, CrSi2 (Micron Metals)", "value": 1490, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "density", "label": "Density, CrSi2 (supplier evaporation material)", "value": 4.91, "bound": "exact", "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", "source_detail": { "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" } }, { "benchmark": "melting_point", "label": "Melting point, NbSi2 (Micron Metals)", "value": 1950, "bound": "exact", "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", "source_detail": { "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" } }, { "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\"", "source_detail": { "title": "Thermoelectric properties of beta-FeSi2 (arXiv 1308.6529)", "url": "https://arxiv.org/pdf/1308.6529", "kind": "paper", "license": "arXiv, cited not reproduced" } } ], "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 } ], "critical_lists": [], "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 } ], "critical_lists": [], "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 } ], "critical_lists": [], "substitutes": [], "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 } ], "critical_lists": [], "substitutes": [], "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 } ], "critical_lists": [], "substitutes": [], "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." ], "story": { "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", "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.", "benchmark": "melting_point", "scope": "material", "value": "2160 degC" }, { "label": "Low resistivity", "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.", "benchmark": "electrical_resistivity", "scope": "material", "value": "12 to 24 uOhm·cm" }, { "label": "Density", "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).", "benchmark": "density", "scope": "material", "value": "9.3 g/cm3" } ], "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", "scope": "material" }, { "label": "Melting point", "benchmark": "melting_point", "scope": "material" }, { "label": "Electrical resistivity", "benchmark": "electrical_resistivity", "scope": "material" } ], "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.", "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", "role": "Two per formula unit. Silicon forms the disilicide lattice with the metal and, in microelectronics contacts, bonds to the silicon substrate.", "atoms": 2, "atomic_weight": 28.085 }, { "name": "Tungsten", "symbol": "W", "role": "The metal in WSi2, which is used for microelectronics contacts and has a melting point of 2160 degC.", "atoms": 1, "atomic_weight": 183.84 }, { "name": "Titanium", "symbol": "Ti", "role": "The metal in TiSi2. The low-resistivity C54 phase is the one used for contacts.", "atoms": 1, "atomic_weight": 47.867 }, { "name": "Tantalum", "symbol": "Ta", "role": "The metal in TaSi2, used in semiconductor metallization.", "atoms": 1, "atomic_weight": 180.9479 }, { "name": "Chromium", "symbol": "Cr", "role": "The metal in CrSi2.", "atoms": 1, "atomic_weight": 51.996 }, { "name": "Niobium", "symbol": "Nb", "role": "The metal in NbSi2, studied as an oxidation-resistant coating for niobium alloys.", "atoms": 1, "atomic_weight": 92.90637 }, { "name": "Iron", "symbol": "Fe", "role": "The metal in beta-FeSi2, a semiconductor studied for thermoelectric use.", "atoms": 1, "atomic_weight": 55.84 } ] }, "risk_groups": [ { "title": "For people", "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)." } ], "level": 0, "verdict": "Irritant reports for CrSi2 and FeSi2" }, { "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." } ] } ] }, "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)." }, "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", "url": "https://spacemushroom.com/profiles/transition-metal-silicides/" }