Molybdenum disilicide

Names
IUPAC name

Molybdenum disilicide

Identifiers

CAS Number

* 12136-78-6 Y

3D model (JSmol)

* Interactive image

ChemSpider |

* 8329647

EC Number |

* 235-231-8

PubChem CID

* 6336985

InChI

* InChI=1S/Mo.2Si

Key: YXTPWUNVHCYOSP-UHFFFAOYSA-N

SMILES

* [Si]=[Mo]=[Si]

Properties

Chemical formula

| MoSi2
Molar mass | 152.11 g/mol
Appearance  | gray metallic solid
Density | 6.26 g/cm3[1][2]
Melting point |  2,030 °C (3,690 °F; 2,300 K)[2]
Structure

Crystal structure

| Tetragonal[1]

Space group

| I4/mmm (No. 139), tI6

Lattice constant

a = 0.32112 nm, c = 0.7845 nm

Formula units (Z)

| 2
Hazards
GHS pictograms |
GHS Signal word | Warning

GHS hazard statements

| H301, H312, H332

GHS precautionary statements

| P261, P264, P270, P271, P280, P301+317Script error: No such module "Preview warning".Category:GHS errors, P302+352, P304+340, P317Script error: No such module "Preview warning".Category:GHS errors, P321, P330, P362+364Script error: No such module "Preview warning".Category:GHS errors, P501
Flash point | Non-flammable
Related compounds

Other cations

| Chromium disilicide
Tungsten disilicide

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

N verify (what is YN ?)
Infobox references

Molybdenum disilicide (MoSi2, or molybdenum silicide), an intermetallic compound, a silicide of molybdenum, is a refractory ceramic with primary use in heating elements. It has moderate density, melting point 2030 °C, and is electrically conductive. At high temperatures it forms a passivation layer of silicon dioxide, protecting it from further oxidation. The thermal stability of MoSi2 alongside its high emissivity make this material, alongside WSi2 attractive for applications as a high emissivity coatings in heat shields for atmospheric entry.[3] MoSi2 is a gray metallic-looking material with tetragonal crystal structure (alpha-modification); its beta-modification is hexagonal and unstable.[4] It is insoluble in most acids but soluble in nitric acid and hydrofluoric acid.

While MoSi2 has excellent resistance to oxidation and high Young's modulus at temperatures above 1000 °C, it is brittle in lower temperatures. Also, at above 1200 °C it loses creep resistance. These properties limits its use as a structural material, but may be offset by using it together with another material as a composite material.

Molybdenum disilicide and MoSi2-based materials are usually made by sintering. Plasma spraying can be used for producing its dense monolithic and composite forms; material produced this way may contain a proportion of β-MoSi2 due to its rapid cooling.

Molybdenum disilicide heating elements can be used for temperatures up to 1800 °C, in electric furnaces used in laboratory and production environment in production of glass, steel, electronics, ceramics, and in heat treatment of materials. While the elements are brittle, they can operate at high power without aging, and their electrical resistivity does not increase with operation time. Their maximum operating temperature has to be lowered in atmospheres with low oxygen content due to breakdown of the passivation layer.[5]

Molybdenum disilicide is used in microelectronics as a contact material. It is often used as a shunt over polysilicon lines to increase their conductivity and increase signal speed.

## See also

* Silicon carbide

## References

1. ↑ 1.0 1.1 A. Nørlund Christensen (1993). "Crystal growth and characterization of the transition metal silicides MoSi2 and WSi2". Journal of Crystal Growth 129 (1–2): 266–268. doi:10.1016/0022-0248(93)90456-7. Bibcode: 1993JCrGr.129..266N.
2. ↑ 2.0 2.1 Soo-Jin Park; Min-Kang Seo (2011). Interface Science and Composites. Academic Press. pp. 563–. ISBN 978-0-12-375049-5. https://books.google.com/books?id=DewhZ53WgLwC&pg=PA563.
3. ↑ High emissivity coatings on fibrous ceramics for reusable space systems Corrosion Science 2019
4. ↑ F. M. d’Heurle, C. S. Petersson, and M. Y. Tsai (1980). "Observations on the hexagonal form of MoSi2 and WSi2 films produced by ion implantation and on related snowplow effects". J. Appl. Phys. 51 (11): 5976–5980. doi:10.1063/1.327517. Bibcode: 1980JAP....51.5976D.
5. ↑ Park, S.J.; Seo, M.K. (2011). Interface Science and Composites. Interface Science and Technology. Elsevier Science. p. 563. ISBN 978-0-12-375049-5. https://books.google.com/books?id=DewhZ53WgLwC&pg=PA563. Retrieved 2023-09-09.

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Molybdenum compounds

Mo(0)|

* Mo(CO)6

Mo(II)|

* MoBr2
* MoCl2
* MoSi2

Mo(III)|

* MoBr3
* MoCl3
* MoI3
* Mo2O3

Mo(IV)|

* MoCl4
* MoF4
* MoO2
* MoS2

Mo(V)|

* MoCl5
* MoF5
* Mo2O5

Mo(VI)|

* MoF6
* MoO3
* MoS3

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*[CID]: Compound ID
*[H301]: Toxic if swallowed
*[H312]: Harmful in contact with skin
*[H332]: Harmful if inhaled
*[P261]: Avoid breathing dust/fume/gas/mist/vapours/spray
*[P264]: Wash … thoroughly after handling
*[P270]: Do not eat, drink or smoke when using this product
*[P271]: Use only outdoors or in a well-ventilated area
*[P280]: Wear protective gloves/protective clothing/eye protection/face protection
*[P302+352]: IF ON SKIN: Wash with soap and water
*[P304+340]: IF INHALED: Remove victim to fresh air and keep at rest in a position comfortable for breathing
*[P321]: Specific treatment (see … on this label)
*[P330]: Rinse mouth
*[P501]: Dispose of contents/container to …
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