Scandium sulfide is a chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 of scandium

Scandium

Scandium is a chemical element with symbol Sc and atomic number 21. A silvery-white metallic transition metal, it has historically been sometimes classified as a rare earth element, together with yttrium and the lanthanoids...

 and sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 with the chemical formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 Sc₂S₃.

Structure

The crystal structure

Crystal structure

In mineralogy and crystallography, crystal structure is a unique arrangement of atoms or molecules in a crystalline liquid or solid. A crystal structure is composed of a pattern, a set of atoms arranged in a particular way, and a lattice exhibiting long-range order and symmetry...

 of Sc₂S₃ is closely related to that of sodium chloride

Sodium chloride

Sodium chloride, also known as salt, common salt, table salt or halite, is an inorganic compound with the formula NaCl. Sodium chloride is the salt most responsible for the salinity of the ocean and of the extracellular fluid of many multicellular organisms...

, in that it is based on a cubic close packed array of anions. Whereas NaCl has all the octahedral interstices in the anion lattice occupied by cations, Sc₂S₃ has one third of them vacant. The vacancies are ordered, but in a very complicated pattern, leading to a large, orthorhombic unit cell belonging to the space group

Space group

In mathematics and geometry, a space group is a symmetry group, usually for three dimensions, that divides space into discrete repeatable domains.In three dimensions, there are 219 unique types, or counted as 230 if chiral copies are considered distinct...

 Fddd.

Synthesis

The normal way to make metal sulfides is simply to mix the two elements and heat them, but in the case of scandium, this method yields scandium monosulfide

Scandium monosulfide

Scandium monosulfide is a chemical compound of scandium and sulfur with the chemical formula ScS. Although its formula might suggest that it is a compound of scandium, i.e...

, ScS. Sc₂S₃ can be prepared by heating scandium(III) oxide

Scandium(III) oxide

Scandium oxide, Sc2O3, scandia is a high melting white solid used in high-temperature systems , electronic ceramics, and glass composition .-Physical and chemical properties:...

 and hydrogen sulfide

Hydrogen sulfide

Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...

 in a graphite

Graphite

The mineral graphite is one of the allotropes of carbon. It was named by Abraham Gottlob Werner in 1789 from the Ancient Greek γράφω , "to draw/write", for its use in pencils, where it is commonly called lead . Unlike diamond , graphite is an electrical conductor, a semimetal...

 crucible

Crucible

A crucible is a container used for metal, glass, and pigment production as well as a number of modern laboratory processes, which can withstand temperatures high enough to melt or otherwise alter its contents...

 to 1550 °C or above for 2–3 hours.

Sc₂O₃ + 3H₂S → Sc₂S₃ + 3H₂O

Reactivity

Above 1100 °C, Sc₂S₃ loses sulfur, forming nonstoichiometric compounds such as Sc_1.37S₂.