Tin-flux technique

A number of binary phosphides and polyphosphides (compounds containing P—P bonds), for instance those of Mn, Tc, Re, Fe, Ru, Os can be prepared, often in well crystallized form, by the tin-flux technique. The mixture generally containing an excess of P (red P) and a high excess of tin is heated, possibly at a slow rate, to the required temperature (600°-1000°C) and maintained at that temperature for several days and then slowly cooled. In several cases the products may be recovered by dissolving the tin-rich residue in hydrochloric acid. The preparation of several ternary phosphides and of arsenides and antimonides has also been described (see 6.11.3). 

Rhenium phosphides with Re-Re bonds (e.g., Re2Ps ResP, ReP, ResPia ) are formed in high temperature reactions of Re metal and red P. Use of the tin flux technique proves advantageous L... 

Several phosphides of technetium were prepared by reaction of technetium metal powder with red phosphorus at 1220 K using the tin-flux technique or iodine as a mineralizer. The preparation was carried out in evacuated, sealed silica tubes. 

Babizhets ky and Kuz ma (1994) constructed the phase diagram of the Ce-Ni-P system at 1070 K (the range with Ce content of 0-33 at.%) and 870 K (the rest of the system) (fig. 23). The compounds CeNi5 (P3 and CegNiePn were not found at the temperatures investigated a single crystal of the former compound was extracted from an arc-melted sample. The latter was synthesized by the tin flux technique. 

Answer by author Even the most "ideal" superconductors such as pure lead and tin appear to trap a few percent of the ambient field during the transition. Commercially available niobium shows almost no Meissner effect. If no steps were taken to enhance the Meissner effect, it would be necessary to reduce the ambient field to 10 gauss. There are a number of techniques that may eliminate flux during the transition, such as rotation or temperature gradients, but at present, I can give no reasonable lower limit on the amount of distribution of frozen flux. 

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