Lanthanum oxide

Preparation

Lanthanum oxide can be produced by direct combustion of lanthanum in oxygen or air. The oxide also may be prepared by decomposition of an oxo salt of lanthanum, such as nitrate, sulfate, carbonate, hydroxide or oxalate. La(CO3)3?8H2O → La2O3 + 3CO2 + 8H2O 2La2(C2O4)3?9H2O + 3O2 → 2La2O3 + 12CO2 + 18H2O

Flammability and Explosibility

Nonflammable

Physical properties

White amorphous powder; density 6.51 g/cm3; melts at 2,305°C; vaporizes at 4,200°C; insoluble in water; dissolves in dilute mineral acids.

General Description

Lanthanum (III) oxide is an alkaline earth oxide, and is a diamagnetic, isostructural analog of neodymium oxide. It is also an efficient recyclable catalyst, and can be used in coupling various aryl halides with aromatic/alkyl thiols.

Industrial uses

Lanthanum oxide (La2O3) has a melting pointof 2250°C, is soluble in acids, and very slightlysoluble in water. This oxide of a rare earth elementoccurs in monazite and bastnasite. It ismarketed as the oxide or as other salts such asthe oxalate, nitrate, or hydrate. It quicklyabsorbs water and CO2 from the atmosphere.Its chief use is as an ingredient in nonsilica,rare element optical glass with oxides of tungsten, tantalum, and thorium. Lanthanumincreases refractive index, decreases dispersion,and is also used in x-ray image intensifyingscreens that speed up x-ray exposure asmuch as two to ten times so that diagnosticdosages may be reduced by as much as 80%with fewer retakes. It is also used in bariumtitanate capacitors.