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Method for production of high-purity samarium metal.
Henrie-TA; Morrice-E Jr.; Murphy-JE
U S Pat 3 524 800 1970 Aug; :
Pure sm is deposited from a fused salt electrolyte of smf3 with lif or an alkaline-earth metal fluoride, in which sm2o3 is dissolved, at a temperature between the melting point of the fluoride bath and that of a fe, ni, or CO cathode, and the sm deposit diffuses into the cathode to form a fluid alloy that drips into a collecting vessel or remains as nodules in the salt bath. The cold alloy, or metal nodules separated from solid barren electrolyte can be heated in a 10-6-10-7 torr vacuum at 800 deg-900 deg c for a fe alloy, or a 1,100 deg-1,200 deg c for a CO or ni alloy, to sublime the sm as vapor that can be solidified on a cooled ta, w, or mo surface from which the sm coating can be peeled. The electrolyte preferably contains 40-90 wt pct smf3 and the alloys generally contain 12-20 pct fe or 20-30 pct CO or ni. In a 1.5 H electrolysis with carbon anodes and a fe cathode in an a.C. Heated bath containing 81 pct smf3 and the balance lif, to which sm2o3 was added, at 960 deg c in a graphite crucible having a 580 deg c bottom temperature and an inert atmosphere, 0.5 A/cm2 was used. The current efficiency was 41 pct. Sm was sublimed by vacuum heating of the nodules as described, with 60 pct recovery as a coating on a cold w cover; and the peeled- off sm metal product contained 10 ppm fe, <100 ppm o, <10 ppm c, and no la or other rare earth.
U.S. Pat. 3,524,800; Aug. 18, 1970; Chem. Abstr. 73:126,483K
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