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Lanthanum oxide

Lanthanum(III) oxide
Lanthanum(III) oxide
La2O3structure.jpg
Names
IUPAC name
Lanthanum(III) oxide
Other names
Lanthanum sesquioxide
Lanthana
Identifiers
ChemSpider
ECHA InfoCard 100.013.819
PubChem CID
RTECS number OE5330000
Properties
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)
Insoluble
Band gap 4.3 eV
−78.0·10−6 cm3/mol
Structure
Hexagonal, hP5
P-3m1, No. 164
Hazards
Main hazards Irritant
R-phrases R36/37
S-phrases S26, S22, S37/39
NFPA 704
Flammability (red): no hazard code Health code 1: Exposure would cause irritation but only minor residual injury. E.g., turpentine Reactivity (yellow): no hazard code Special hazard W: Reacts with water in an unusual or dangerous manner. E.g., cesium, sodiumNFPA 704 four-colored diamond
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).
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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.


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