Samarium(III) oxide ( Sm₂ O₃) is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

. Samarium oxide readily forms on the surface of

samarium Samarium is a chemical element; it has symbol Sm and atomic number 62. It is a moderately hard silvery metal that slowly oxidizes in air. Being a typical member of the lanthanide series, samarium usually has the oxidation state +3. Compounds of s ...

metal under humid conditions or temperatures in excess of 150°C in dry air. Similar to rust on metallic iron, this oxide layer spalls off the surface of the metal, exposing more metal to continue the reaction. The oxide is commonly white to off yellow in color and is often encountered as a highly fine dust like powder.

Uses

Samarium(III) oxide is used in optical and infrared absorbing glass to absorb

infrared radiation Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with the waves that are just longer than those ...

. Also, it is used as a

neutron The neutron is a subatomic particle, symbol or , that has no electric charge, and a mass slightly greater than that of a proton. The Discovery of the neutron, neutron was discovered by James Chadwick in 1932, leading to the discovery of nucle ...

absorber in control rods for nuclear power reactors. The oxide catalyzes the dehydration and dehydrogenation of primary and secondary alcohols. Another use involves preparation of other samarium salts.Pradyot Patnaik. ''Handbook of Inorganic Chemicals''. McGraw-Hill, 2002,

Preparations

Samarium(III) oxide may be prepared by two methods: 1.

thermal decomposition Thermal decomposition, or thermolysis, is a chemical decomposition of a substance caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic ...

of samarium(III) carbonate, hydroxide, nitrate, oxalate or sulfate: : Sm₂(CO₃)₃ → Sm₂O₃ + 3 CO₂ 2. by burning the metal in air or oxygen at a temperature above 150 °C: : 4 Sm + 3 O₂ → 2 Sm₂O₃

Reactions

Samarium(III) oxide dissolves in mineral acids, forming salts upon

evaporation Evaporation is a type of vaporization that occurs on the Interface (chemistry), surface of a liquid as it changes into the gas phase. A high concentration of the evaporating substance in the surrounding gas significantly slows down evapora ...

and

crystallization Crystallization is a process that leads to solids with highly organized Atom, atoms or Molecule, molecules, i.e. a crystal. The ordered nature of a crystalline solid can be contrasted with amorphous solids in which atoms or molecules lack regu ...

: : Sm₂O₃ + 6 HCl → 2 SmCl₃ + 3 H₂O The oxide can be reduced to metallic samarium by heating with a

reducing agent In chemistry, a reducing agent (also known as a reductant, reducer, or electron donor) is a chemical species that "donates" an electron to an (called the , , , or ). Examples of substances that are common reducing agents include hydrogen, carbon ...

, such as hydrogen or

carbon monoxide Carbon monoxide (chemical formula CO) is a poisonous, flammable gas that is colorless, odorless, tasteless, and slightly less dense than air. Carbon monoxide consists of one carbon atom and one oxygen atom connected by a triple bond. It is the si ...

, at elevated temperatures.

References

{{Oxides Sesquioxides Crystals in space group 206 Samarium(III) compounds