Europium (II) sulfide is the inorganic compound with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

EuS. It is a black, air-stable

powder A powder is a dry, bulk solid composed of many very fine particles that may flow freely when shaken or tilted. Powders are a special sub-class of granular materials, although the terms ''powder'' and '' granular'' are sometimes used to distin ...

. Europium possesses an

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical charge of an atom if all of its bonds to different atoms were fully ionic. It describes the degree of oxidation (loss of electrons) of an atom in a chemical compound. C ...

of +II in europium sulfide, whereas the lanthanides exhibit a typical oxidation state of +III.C. Housecroft. Inorganic Chemistry. 3rd. Essex, England: Pearson Education Limited, 2008. Print. Its

Curie temperature In physics and materials science, the Curie temperature (''T''C), or Curie point, is the temperature above which certain materials lose their permanent magnetic properties, which can (in most cases) be replaced by induced magnetism. The Cur ...

(T_c) is 16.6 K. Below this temperature EuS behaves like a ferromagnetic compound, and above it exhibits simple

paramagnetic Paramagnetism is a form of magnetism whereby some materials are weakly attracted by an externally applied magnetic field, and form internal, induced magnetic fields in the direction of the applied magnetic field. In contrast with this behavior, ...

properties. EuS is stable up to 500 °C in air, when it begins to show signs of

oxidation Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

. In an inert environment it decomposes at 1470 °C.

Structure

EuS crystallizes in

face-centered cubic In crystallography, the cubic (or isometric) crystal system is a crystal system where the unit cell is in the shape of a cube. This is one of the most common and simplest shapes found in crystals and minerals. There are three main varieties of ...

(FCC) crystal lattice with the rock salt structure. Both europium and sulfur have

octahedral coordination geometry In chemistry, octahedral molecular geometry, also called square bipyramidal, describes the shape of compounds with six atoms or groups of atoms or ligands symmetrically arranged around a central atom, defining the vertices of an octahedron. The oc ...

with a

coordination number In chemistry, crystallography, and materials science, the coordination number, also called ligancy, of a central atom in a molecule or crystal is the number of atoms, molecules or ions bonded to it. The ion/molecule/atom surrounding the central io ...

of six.Wells A.F. Structural Inorganic Chemistry. 5th. London, England: Oxford University Press, 1984. Print. The Eu-S bond lengths are 2.41 Å.

Preparation

In the preparation of EuS, powdered

europium(III) oxide Europium(III) oxide (Eu2O3), is a chemical compound of europium and oxygen. It is widely used as a red or blue phosphor in television sets and fluorescent lamps, and as an activator for yttrium-based phosphors. It is also an agent for the manufac ...

(Eu₂O₃) is treated with hydrogen sulfide (H₂S) at 1150 °C. The crude EuS product is purified by heating at 900 °C under vacuum to remove excess sulfur.Archer, R. D. Mitchel, W. N. Inorganic Syntheses, Europium (II) Sulfide. 1967, volume 10, 77-79. :Eu₂O₃ + 3 H₂S → 2 EuS + 3 H₂O + S EuS has additionally been synthesized from europium dichloride (EuCl₂), however, such products tend to be contaminated by

chloride The chloride ion is the anion (negatively charged ion) Cl−. It is formed when the element chlorine (a halogen) gains an electron or when a compound such as hydrogen chloride is dissolved in water or other polar solvents. Chloride sa ...

Research

In the past few decades, a new interest has been exhibited in the synthesis of EuS, as well as its

oxygen Oxygen is the chemical element with the symbol O and atomic number 8. It is a member of the chalcogen group in the periodic table, a highly reactive nonmetal, and an oxidizing agent that readily forms oxides with most elements as ...

analog EuO, because of their potential as laser window materials, insulating ferromagnets, ferromagnetic semiconductors, and magnetoresistant, optomagnetic, and

luminescent Luminescence is spontaneous emission of light by a substance not resulting from heat; or "cold light". It is thus a form of cold-body radiation. It can be caused by chemical reactions, electrical energy, subatomic motions or stress on a crystal ...

materials. EuS was used in an experiment providing evidence of Majorana fermions relevant to quantum computing and the production of

qubits In quantum computing, a qubit () or quantum bit is a basic unit of quantum information—the quantum version of the classic binary bit physically realized with a two-state device. A qubit is a two-state (or two-level) quantum-mechanical system, ...

References

{{Sulfur compounds Europium(II) compounds Monosulfides Rock salt crystal structure