Copper(I) sulfide
Copper(I) sulfide is a copper sulfide, a chemical compound of copper and sulfur. It has the chemical compound Cu2S. It is found in nature as the mineral chalcocite. It has a narrow range of stoichiometry ranging from Cu1.997S to Cu2.000S.[1] Samples are typically black.
Preparation and reactions
Cu2S can be prepared by treating copper with sulfur or H2S.[2] The rate depends on the particle size and temperature.[3] Cu2S reacts with oxygen to form SO2:[4]
The production of copper from chalcocite is a typical process in extracting the metal from ores. Usually, the conversion involves roasting, to give Cu2O and sulfur dioxide:[4]
Copper (I) oxide oxide readily converts to copper (II) oxide when heated in the presence of oxygen, and to copper metal upon heating in a reducing environment. (cf. Carbothermic reduction)
Structure
Stoichiometric
Two forms (a dimorphism) of Cu2S are known. The so-called low temperature monoclinic form ("low-chalcocite") has a complex structure with 96 copper atoms in the unit cell.[5] The hexagonal form, stable above 104 °C,[6] has 24 crystallographically distinct Cu atoms. Its structure has been described as approximating to a hexagonal close packed array of sulfur atoms with Cu atoms in planar 3 coordination. This structure was initially assigned an orthorhombic cell due to the twinning of the sample crystal.
Non-stoichiometric
As illustrated by the mineral djurleite, a cuprous sulfide is also known. With the approximate formula Cu1.96S, this material is non-stoichiometric (range Cu1.934S-Cu1.965S) and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell.[5] Cu2S and Cu1.96S are similar in appearance and hard to distinguish one from another.[7]
Phase transition
The electrical resistivity increases abruptly at the phase transition point around 104 °C, with the precise temperature depending on the stoichiometry.[8][9]
See also
- Copper sulfide for an overview of all copper sulfide phases
- Copper monosulfide, CuS
- Chalcocite
- Djurleite
- LK-99 - compound evaluated in 2023 for possible superconductivity
References
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- ↑ a b Wiberg, Egon and Holleman, Arnold Frederick (2001) Inorganic Chemistry, Elsevier Template:ISBN
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- ↑ Wells A.F. (1984) Structural Inorganic Chemistry, 5th ed., Oxford Science Publications, Template:ISBN
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- ↑ Jain, Prashant K. "Phase transition of copper (I) sulfide and its implication for purported superconductivity of LK-99." arXiv preprint arXiv:2308.05222 (2023).
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