Europium(II) sulfide
Encyclopedia
Europium sulfide is the inorganic compound
with the chemical formula
EuS. It is a black, air-stable powder
. Europium possesses an oxidation state
of +II in europium sulfide, whereas the lanthanide
s exhibit a typical oxidation state of +III. Its Curie temperature (Tc) is 16.6 K. Below this temperature EuS behaves like a ferromagnetic compound, and above it exhibits simple paramagnetic
properties. EuS is stable up to 500 °C in air, when it begins to show signs of oxidation. In an inert environment it decomposes at 1470 °C.
and sulfur
have octahedral coordination geometry with a coordination number
of six. The Eu-S bond lengths are 2.41 Å.
(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.
EuS has additionally been synthesized from europium dichloride (EuCl2), however, such products tend to be contaminated by chloride
.
analog EuO, because of their potential use as laser window materials, insulating ferromagnets, ferromagnetic semiconductors, and magnetoresistant
, optomagnetic, and luminescent
materials.
Inorganic compound
Inorganic compounds have traditionally been considered to be of inanimate, non-biological origin. In contrast, organic compounds have an explicit biological origin. However, over the past century, the classification of inorganic vs organic compounds has become less important to scientists,...
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....
EuS. It is a black, air-stable powder
Powder
Powder may refer to:*Powder , material composed of very fine particles that are not cemented together* Powder , a 1995 film* Powder , a mid-1990s Britpop band* Powder blue, a color...
. Europium possesses an oxidation state
Oxidation state
In chemistry, the oxidation state is an indicator of the degree of oxidation of an atom in a chemical compound. The formal oxidation state is the hypothetical charge that an atom would have if all bonds to atoms of different elements were 100% ionic. Oxidation states are typically represented by...
of +II in europium sulfide, whereas the lanthanide
Lanthanide
The lanthanide or lanthanoid series comprises the fifteen metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium...
s exhibit a typical oxidation state of +III. Its Curie temperature (Tc) is 16.6 K. Below this temperature EuS behaves like a ferromagnetic compound, and above it exhibits simple paramagnetic
Paramagnetism
Paramagnetism is a form of magnetism whereby the paramagnetic material is only attracted when in the presence of an externally applied magnetic field. In contrast with this, diamagnetic materials are repulsive when placed in a magnetic field...
properties. EuS is stable up to 500 °C in air, when it begins to show signs of oxidation. In an inert environment it decomposes at 1470 °C.
Structure
EuS crystallizes in face-centered cubic (FCC) crystal lattice. Both europiumEuropium
Europium is a chemical element with the symbol Eu and atomic number 63. It is named after the continent of Europe. It is a moderately hard silvery metal which readily oxidizes in air and water...
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...
have octahedral coordination geometry with a coordination number
Coordination number
In chemistry and crystallography, the coordination number of a central atom in a molecule or crystal is the number of its nearest neighbours. This number is determined somewhat differently for molecules and for crystals....
of six. The Eu-S bond lengths are 2.41 Å.
Preparation
In the preparation of EuS, powdered europium(III) oxideEuropium(III) oxide
Europium oxide , 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 manufacture of fluorescent glass. Europium fluorescence is used in the...
(Eu2O3) is treated with 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...
(H2S) at 1150 °C. The crude EuS product is purified by heating at 900 °C under vacuum to remove excess sulfur.
- 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
Chloride
The chloride ion is formed when the element chlorine, a halogen, picks up one electron to form an anion Cl−. The salts of hydrochloric acid HCl contain chloride ions and can also be called chlorides. The chloride ion, and its salts such as sodium chloride, are very soluble in water...
.
Applications
In the past few decades, a new interest has been exhibited in the synthesis of EuS, as well as its oxygenOxygen
Oxygen is the element with atomic number 8 and represented by the symbol O. Its name derives from the Greek roots ὀξύς and -γενής , because at the time of naming, it was mistakenly thought that all acids required oxygen in their composition...
analog EuO, because of their potential use as laser window materials, insulating ferromagnets, ferromagnetic semiconductors, and magnetoresistant
Magnetoresistance
Magnetoresistance is the property of a material to change the value of its electrical resistance when an external magnetic field is applied to it. The effect was first discovered by William Thomson in 1856, but he was unable to lower the electrical resistance of anything by more than 5%. This...
, optomagnetic, and luminescent
Luminescence
Luminescence is emission of light by a substance not resulting from heat; 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. This distinguishes luminescence from incandescence, which is light emitted by a...
materials.