Fermium can be separated from einsteinium and californium by reducing it with metallic magnesium in hydrochloric acid-acetic acid followed by co-crystallization with samarium dichloride: Method For Recovering Fermium (1993).
To obtain fermium in the divalent state a hydrochloric acid-ethanol water solution of trivalent fermium is treated with samarium trichloride and metallic magnesium: Method Of Preparing Fermium In A Bivalent State (1979)).
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