| Crystal Bar Process |
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| CATEGORIES ABOUT CRYSTAL BAR PROCESS | |
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| zirconium | |
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Impure titanium or zirconium is heated in an evacuated vessel with iodine at 50-250oC. Titanium or zirconium iodide (TiI4 or ZrI4 ) is formed and is volatilized (leaving impurities as solid). At atmospheric pressure TiI4 melts at 150oC and boils at 377oC, while ZrI4 melts ar 499oC and boils at 600oC. The boiling points are lower at reduced pressure. The gaseous metal tetraiodide is decomposed on a white hot tungsten filament (1400oC). As more metal is deposited the filament conducts better and thus a greater electric current is required to maintain the temperature of the filament. |
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