Lanthana

Lanthanum(III) oxide

Names
IUPAC name Lanthanum(III) oxide
Other names Lanthanum sesquioxide Lanthana
Identifiers
CAS Number	1312-81-8 Y
ChemSpider	2529886 Y 133008 Y
ECHA InfoCard	100.013.819
PubChem	150906
RTECS number	OE5330000
InChI InChI=1S/2La.3O Y Key: KTUFCUMIWABKDW-UHFFFAOYSA-N Y
Properties
Chemical formula	La2O3
Molar mass	325.809 g/mol
Appearance	White powder, hygroscopic
Density	6.51 g/cm3, solid
Melting point	2,315 °C (4,199 °F; 2,588 K)
Boiling point	4,200 °C (7,590 °F; 4,470 K)
Solubility in water	Insoluble
Band gap	4.3 eV
Magnetic susceptibility (χ)	−78.0·10−6 cm3/mol
Structure
Crystal structure	Hexagonal, hP5
Space group	P-3m1, No. 164
Hazards
Main hazards	Irritant
R-phrases	R36/37
S-phrases	S26, S22, S37/39
NFPA 704	1 W
Flash point	Non-flammable
Related compounds
Other anions	Lanthanum(III) chloride
Other cations	Cerium(III) oxide Scandium(III) oxide Yttrium(III) oxide Actinium(III) oxide
Related compounds	Lanthanum aluminium oxide, LaSrCoO4
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Lanthanum oxide is La₂O₃, an inorganic compound containing the rare earth element lanthanum and oxygen. It is used to develop ferroelectric materials, as a component of optical materials, and is a feedstock for certain catalysts.

La₂O₃ has a band gap at approximately 5.8 eV. It has the lowest lattice energy, with very high dielectric constant, ε = 27. La₂O₃ is widely used in industry as well as in the research laboratory. Lanthanum oxide is an odorless, white solid that is insoluble in water, but soluble in dilute acid. Depending on the pH of the compound, different crystal structures can be obtained. La₂O₃ is hygroscopic; under atmosphere, lanthanum oxide absorbs moisture over time and converts to lanthanum hydroxide. Lanthanum oxide has p-type semiconducting properties. Its resistivity decreases with an increase in temperature. Its average room temperature resistivity is 10 kΩ·cm.

At low temperatures, La₂O₃ has an A-M₂O₃ hexagonal crystal structure. The La³⁺ metal atoms are surrounded by a 7 coordinate group of O²⁻atoms, the oxygen ions are in an octahedral shape around the metal atom and there is one oxygen ion above one of the octahedral faces. On the other hand, at high temperatures the Lanthanum oxide converts to a C-M₂O₃ cubic crystal structure. The La³⁺ ion is surrounded by a 6 coordinate group of O²⁻ ions.

There are several elements which were discovered as a consequence of the lengthy analysis and breakdown of the ore Gadolinite. As the ore was progressively analysed further, the residue was given the label thence ceria and thence lanthana and onwards to yttria, erbia, and terbia. The list by date includes Cerium 58, Lanthanum 57, Erbium 68, Terbium 65, Yttrium 39, Ytterbium 70, Holmium 67, Thulium 69, Scandium 21, Praseodymium 59, Neodymium 60 and Dysprosium 66. Several of these new elements were either discovered or isolated by Carl Gustaf Mosander in the 1830s and 1840s.