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Lanthanum is a chemical element with the symbol La and the atomic number 57. It is a soft, ductile, silvery-white metal that tarnishes slowly when exposed to air. It is the eponym of the lanthanide series, a group of 15 similar elements between lanthanum and lutetium in the periodic table, of which lanthanum is the first and the prototype.
Naturally occurring lanthanum (57 La) is composed of one stable (139 La) and one radioactive (138 La) isotope, with the stable isotope, 139 La, being the most abundant (99.91% natural abundance). There are 39 radioisotopes that have been characterized, with the most stable being 138 La, with a half-life of 1.03×10 11 years; 137 La, with a half ...
Lanthanum-140 has a specific activity of 5.57×10 5 Ci/g (20.6 PBq/g); a 1,000 Ci (37 TBq) La-140 source therefore equals about 1.8 mg of lanthanum. [ 1 ] A radiolanthanum sample, precipitated in a tip of a small cone, followed by a plug, was lowered into the center of the metal sphere of the experimental assembly with a device resembling a ...
Today, the Indian and South African deposits still produce some rare-earth concentrates, but they were dwarfed by the scale of Chinese production. In 2017, China produced 81% of the world's rare-earth supply, mostly in Inner Mongolia , [ 8 ] [ 43 ] although it had only 36.7% of reserves.
Lanthanum(III) sulfate is an inorganic compound with the formula La 2 (SO 4) 3 ·xH 2 O (0 ≥ x ≥ 9). It forms various hydrates, the most common one being the nonahydrate, which are all white solids.
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The first enduring commercial use of purified praseodymium, which continues today, is in the form of a yellow-orange "Praseodymium Yellow" stain for ceramics, which is a solid solution in the zircon lattice. This stain has no hint of green in it; by contrast, at sufficiently high loadings, praseodymium glass is distinctly green rather than pure ...
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