Single Crystals of Iron Monophosphide

Submitted by DAVID W. BELLA VANCE and AARON WOLDf Checked by WALTER KUNNMANN  

The various techniques for the synthesis of transition metal phosphides have been summarized in the monograph by Aronsson, Lundstrom, and Rundqvist.1 The most common method used for the preparation of the phosphides is the direct combination of the elements. However, in general, the products are not pure or 

Six grams (0.053 mole) of iron(III) fluoride is mixed thoroughly with 60 g. (0.1 mole) of purified-grade sodium meta-phosphatet in a beaker and the contents are transferred to the carbon crucible. The crucible is placed in the reaction chamber and is heated to 925°C. at the rate of 75°C./hour in a flowing argon atmosphere. The crucible is allowed to equilibrate at 925°C. for 1 hour. The center electrode is inserted to a depth of in. and a current of 250 mA. (61 mA./cm.2) is used. A constant current source is used to maintain the desired current. The electrolysis should be carried out from 12 to 24 hours to give a sufficient yield. After electrolysis the melt is cooled to room temperature at the rate of 75°C./hour. The crucible is cut to expose the reaction boule, and the excess melt is removed by leaching in hot, dilute hydrochloric acid. Free carbon is removed by flotation with methylene iodide(diiodomethane). The product is in the form of metallic needles and small crystallites with a yield of 0.5-1 g. 

Aronsson, T. Lundstrom, and S. Rundqvist, Borides, Silicides, and Phosphides, John Wiley Sc Sons, Inc., New York, 1965. 

Bellavance, M. Vlasse, B. Morris, and A. Wold, /. Solid-State Chem., 1, 82 (1969). 

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