Оксид лантана(III): свойства, структура и применение

Chemical compound
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| Name = Lanthanum(III) oxide
| ImageFile = Oxyde de lanthane en poudre. jpg
| ImageFile2 = La2O3structure. jpg
| ImageName = Lanthanum(III) oxide
| IUPACName = Lanthanum(III) oxide
| OtherNames = Lanthanum sesquioxideLanthana
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Lanthanum oxide has p type semiconducting properties and a band gap of approximately 5.8 eV. Its average room temperature resistivity is 10 kΩ·cm, which decreases with an increase in temperature. |La2O3 has the lowest lattice energy of the rare earth oxides, with very high dielectric constant, ε = 27.

At low temperatures, |La2O3 has an A |M2O3 hexagonal crystal structure. The |La(3+) metal atoms are surrounded by a 7 coordinate group of |O(2−) 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 lanthanum oxide converts to a C |M2O3 cubic crystal structure. The |La(3+) ion is surrounded by six |O(2−) ions in a hexagonal configuration.

Lanthanum oxide is most useful as a precursor to other lanthanum compounds. Neither the oxide nor any of the derived materials enjoys substantial commercial value, unlike some of the other lanthanides. Many reports describe efforts toward practical applications of |La2O3, as described below. |La2O3 forms glasses of high density, refractive index, and hardness. Together with oxides of tungsten, tantalum, and thorium, |La2O3 improves the resistance of the glass to attack by alkali. |La2O3 is an ingredient in some piezoelectric and thermoelectric materials.<! untrue, that is cerium: Automobile exhaust gas converters contain |La2O3. |La2O3 is also used in X ray imaging intensifying screens, phosphors as well as dielectric and conductive ceramics. Gives off bright glow. |La2O3 films can be deposited by many different methods, including chemical vapor disposition, atomic layer deposition, thermal oxidation, sputtering, and spray pyrolysis. Depositions of these films occur in a temperature range of 250–450 °C. Polycrystalline films are formed at 350 °C.