Molybdenum diselenide
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 Top-view atomic images of MoSe2 before and after (right) ion irradiation
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| Names | |
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IUPAC name
bis(selanylidene)molybdenum
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| Other names
molybdenum diselenide, molybdenumdiselenide, molybdenum selenide, diselanylidenemolybdenum
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| Identifiers | |
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3D model (Jmol)
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| ECHA InfoCard | 100.031.831 |
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PubChem CID
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| Properties | |
| MoSe 2 |
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| Molar mass | 253.86 g/mol |
| Appearance | crystalline solid |
| Density | 6.90 g/cm3 |
| Melting point | >1200 °C |
| Band gap | ~0.85 eV (indirect, bulk) ~1.5 eV (direct, monolayer) |
| Structure | |
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hP6, space group P6 3/mmc, No 194 |
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a = 0.3283 nm, c = 1.2918 nm
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Trigonal prismatic (WIV) Pyramidal (Se2−) |
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| Related compounds | |
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Other anions
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Molybdenum dioxide Molybdenum disulfide Molybdenum ditelluride |
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Other cations
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Tungsten diselenide |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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| Infobox references | |
Molybdenum diselenide (MoSe
2) is an inorganic compound of molybdenum and selenium. Its structure is similar to that of MoS
2. Compounds of this category are known as transition metal dichalcogenides, abbreviated TMDCs. These compounds, as the name suggests, are made up of a transition metals and elements of group 16 on the periodic table of the elements.
Like many TMDCs, MoSe
2 is a layered material with strong in-plane bonding and weak out-of-plane interactions. These interactions lead to exfoliation into two-dimensional layers of single unit cell thickness.
The most common form of these TMDCs have trilayers of molybdenum sandwiched between selenium ions causing a trigonal prismatic metal bonding coordination, but it is octahedral when the compound is exfoliated. The metal ion in these compounds is surrounded by six Se2−
ions. The coordination geometry of the Mo is sometimes found as octahedral and trigonal prismatic.
Synthesis of MoSe
2 involves direct reaction of molybdenum and selenium in a sealed tube at high temperature. Chemical vapor transport with a halogen (usually bromine or iodine) is used to purify the compound at very low pressure (less than 10-6 torr) and very high temperature (600–700 °C). It has to be heated very gradually to prevent explosion due to its strong exothermic reaction. Stoichiometric layers crystallize in a hexagonal structure as the sample cools. Excess selenium can be removed by sublimation under vacuum. The synthesis reaction of MoSe
2 is:
...
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