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 with 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 samar ...

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 those of visible light. It is therefore invisible to the human eye. IR is generally understood to encompass wavelengths from around ...

. Also, it is used as a

neutron The neutron is a subatomic particle, symbol or , which has a neutral (not positive or negative) charge, and a mass slightly greater than that of a proton. Protons and neutrons constitute the nuclei of atoms. Since protons and neutrons beh ...

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 caused by heat. The decomposition temperature of a substance is the temperature at which the substance chemically decomposes. The reaction is usually endothermic as heat is re ...

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 and crystallization: : 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 commonly reducing agents include the Earth me ...

, such as hydrogen or

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

, at elevated temperatures.

References

Samarium compounds Sesquioxides {{inorganic-compound-stub