Lanthanum disilicide
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| Other names
Lanthanum silicide
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3D model (JSmol)
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| Properties | |
| LaSi2 | |
| Molar mass | 195.075 g·mol−1 |
| Appearance | gray crystals |
| Density | 5.05 g/cm3 |
| Melting point | 1,500[1] °C (2,730 °F; 1,770 K) |
| insoluble | |
| Structure | |
| Tetragonal, orthorhombic | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Lanthanum disilicide is a binary inorganic compound of lanthanum metal and silicon with the formula LaSi2. Many other lanthanum silicides are known.[2]
Synthesis
[edit]- Combine silicon and lanthanum powders, compress the mixture into solid blocks, and melt under vacuum conditions.[3]
- React lanthanum, silicon, and mercury in a quartz tube at 450 °C for 10–12 hours. Subsequently, eliminate surplus mercury through distillation, followed by annealing the resultant material at 450–600 °C.[3]
Physical properties
[edit]Lanthanum disilicide forms gray crystals. LaSi2 can exist in two crystal structures: tetragonal (α-GdSi2 type) and orthorhombic (α-ThSi2 type).[1][4]
The compound is known for its metallic behavior and various applications.[5]
Chemical properties
[edit]LaSi2 reacts with hydrochloric acid and hydrofluoric acid; insoluble in water.[3]
Uses
[edit]The LaSi2-powder is characterized by high electrical resistivity, minimal thermal expansion, and outstanding thermal stability. These properties make it potentially useful for applications in electric heating devices, high-temperature sensors, refractory ceramics, thermal tools, and materials designed for efficient heat conduction.[3]
References
[edit]- ^ a b Bulanova, M. V.; Zheltov, P. N.; Meleshevich, K. A.; Saltykov, P. A.; Effenberg, G.; Tedenac, J. -C. (14 November 2001). "Lanthanum–silicon system". Journal of Alloys and Compounds. 329 (1): 214–223. doi:10.1016/S0925-8388(01)01686-3. ISSN 0925-8388. Retrieved 20 June 2025.
- ^ Sicius, Hermann (28 October 2024). Handbook of the Chemical Elements. Springer Nature. p. 902. ISBN 978-3-662-68921-9. Retrieved 20 June 2025.
- ^ a b c d "Lanthanum Disilicide Powder, LaSi2, CAS 12056-90-5 - Heeger Materials". Heeger Materials. Retrieved 20 June 2025.
- ^ Rud', B. M.; Paderno, Yu. B. (January 1967). "Physical properties of lanthanum disilicide in the homogeneity region". Soviet Powder Metallurgy and Metal Ceramics. 6 (1): 62–64. doi:10.1007/BF00773384. Retrieved 20 June 2025.
- ^ Long, Robert G.; Bost, M. C.; Mahan, John E. (3 October 1988). "Metallic behavior of lanthanum disilicide". Applied Physics Letters. 53 (14): 1272–1273. Bibcode:1988ApPhL..53.1272L. doi:10.1063/1.100447. ISSN 0003-6951. Retrieved 20 June 2025.