Copper(I) sulfide

Preparation and reactions

can be prepared by treating copper with sulfur or . The rate depends on the particle size and temperature. reacts with oxygen to form : :

The production of copper from chalcocite is a typical process in extracting the metal from ores. Usually, the conversion involves roasting, to give as an intermediate which is further reduced to the metal, and sulfur dioxide: : Copper(I) 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 are known. The so-called low temperature monoclinic form ("low-chalcocite") has a complex structure with 96 copper atoms in the unit cell. The hexagonal form, stable above 104 C, 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 , this material is non-stoichiometric (range - and has a monoclinic structure with 248 copper and 128 sulfur atoms in the unit cell.

Phase transition

The electrical resistivity increases abruptly at the phase transition point around 104 C, with the precise temperature depending on the stoichiometry.

References

References

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2. {{Greenwood&Earnshaw1st
3. {{Sigma-Aldrich
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8. (1979). "Djurleite (Cu_1.94S) and Low Chalcocite (Cu₂S): New Crystal Structure Studies". Science.
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