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Lanthanum oxide

Lanthanum oxide, also known as lanthana, chemical formula La2O3, is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock for certain catalysts, among other uses. Lanthanum oxide, also known as lanthana, chemical formula La2O3, is an inorganic compound containing the rare earth element lanthanum and oxygen. It is used in some ferroelectric materials, as a component of optical materials, and is a feedstock for certain catalysts, among other uses. 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, it absorbs moisture over time and converts to lanthanum hydroxide. 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 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 lanthanum oxide converts to a C-M2O3 cubic crystal structure. The La3+ ion is surrounded by six O2− ions in a hexagonal configuration. Several elements were discovered as a consequence of lengthy analysis and decomposition of the ore Gadolinite. As the ore was progressively analysed, the residue was first given the label ceria and then lanthana and then subsequently yttria, erbia, and terbia. In order of date discovered, the list of elements 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. Lanthanum oxide can be crystallized in several polymorphs. To produce hexagonal La2O3, a 0.1 M solution of LaCl3 is sprayed onto a preheated substrate, usually made of metal chalcogenides. The process can be viewed as occurring in two steps – hydrolysis followed by dehydration: An alternative route to obtaining hexagonal La2O3 involves precipitation of nominal La(OH)3 from aqueous solution using a combination of 2.5% NH3 and the surfactant sodium dodecyl sulfate followed by heating and stirring for 24 hours at 80 °C:

[ "Catalysis", "Lanthanum", "Oxide" ]
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