Preparation in Niobium Tubes

The niobium tube is crimped and welded at one side s (see Fig. 2a, Ref. 5), then cleaned. After filling with sodium and red amorphous phosphorus under inert conditions, it is crimped and welded at the other side. 

The heating is performed in an evacuated fused-silica jacket (Fig. Ic). Typical heating temperatures are 50 h up to 600°, holding 2 days at that temperature, cooling within 1 day to room temperature. 

Because of the less pronounced reaction of sodium with the niobium tube, no excess sodium is necessary. Grinding of the initial reaction product and a second reaction helps to achieve complete reaction. 

For the transfer of alkali metals under inert conditions, see, e.g. (a) A. Simon, in Handhuch der Praparativen Anorganischen Chemie, Vol, 3, G. Brauer (ed.), Auflage, Ferdinand Enke Verlag, Stuttgart, 1978, Chapter 17 (b) A. Simon, W. Bramer, B. Hillenkotter, and H.-J. Kullman, Z. Anorg. Allg. Chemie, 419, 253 (1976). 

Henkel, K. Strossner, H. D. Hochheimer, W. Hdnle, and H. G. von Schnering, Proceedings of the 8th International Conference of Raman Spectroscopy, France, Sept. 1982, Wiley, New York, 1982 p. 459. 

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