Author: Jan Scholten
3.0 Lanthanum physical
Lanthanum is silvery white, malleable, ductile, and soft enough to be cut with a knife. It is one of the most reactive of the rare-earth metals. It oxidizes rapidly when exposed to air. Cold water attacks lanthanum slowly, and hot water attacks it much more rapidly. The metal reacts directly with elemental carbon, nitrogen, boron, selenium, silicon, phosphorus, sulphur, and with halogens. It is a component of mischmetal (used for making lighter flints).
Atomic number: 57.
Discovered: 1839, Carl Gustaf Mosander, Sweden.
Name: “lanthanein” Greek for “to lie hidden”.
Toxicology: mildly toxic by ingestion, and causes liver injury.
Glycohemia, low blood pressure, degeneration of the spleen.
Ore: Monazite (Ce, La, Th, Nd, Y)PO4, Bastnasite (Ce, La, Y)CO3F
1. Carbon lighting applications, especially by the motion picture industry for studio lighting and projection.
2. 203La improves the alkali resistance of glass, and is used in making special optical glasses.
3. Infrared absorbing glass.
4. Camera and telescope lenses, because of the high refractive index and low dispersion of rare-earth glasses.
5. Small amounts as an additive are used to produce nodular cast iron
6. Hydrogen sponge alloys containing lanthanum reversibly take up to 400 times their own volume of hydrogen gas. Heat is released, therefore these alloys have potential in energy conservation systems
7. Lighter flints
8. Small amounts of lanthanum added to steel improves its malleability, resistance to impact and ductility.
9. Small amounts of lanthanum added to molybdenum decreases the hardness of this metal and its sensitivity to temperature variations.
10. Mischmetal, a pyrophoric alloy used e.g. in lighter flints, contains 25% to 45% lanthanum.
11. The oxide and the boride are used in electronic vacuum tubes.
12. Petroleum cracking catalysts.
13. Gas lantern mantles.
14. Glass and lapidary polishing compound.
15. La-Ba age dating of rocks and ores.
16. Lanthanum nitrate is mainly applied in specialty glass, water treatment and catalyst.