Zur Theorie der Rekristallisation

Abstract

1 l) 2 rs = f lo p A. EUCKEN, Chem. Physik, Leipzig 1930,644. Eine genaue Berechnung von ZI ist unmtiglich, das owohl der Atomabstand als auch der Durchmesser der Wirkungsspharen sich mit der Temperatur andern. Beim Schmelzpunkt wird r,, sich immer mehr r, nahern. welche als Losung ergibt2) : oder da l) J.

The structure of β-tungsten hexachloride by powder neutron and X-ray diffraction

“…Liempt (1931) reported the transition temperature to be 228 °C, although experiments described in this paper indicate that this might be high. The higher density of ~-WCI 6 (Table 1) is also consistent with its being the lower temperature form.…”

“…Although a phase change at 228°C had been observed by Liempt (1931), the structure of the second polymorph of WC16 was not investigated until recently (Smith, Landingham, Smith & Johnson, 1968). These authors found a hexagonal polymorph of WC16 with a=10.511 (3) A and c=5.757 (1) A, (Table 1), the cell being similar to that of UCI6 which has the hexagonal space group P3ml and a= 10.…”

“…A small sample of fl-WC16, with a larger crystal size than that prepared above, was formed by subliming WC16 slowly at 150°C in a N2 atmosphere within a sealed tube. This observation suggested that the temperature of the phase change in WCI6 was lower than the reported temperature of 228°C (Liempt, 1931). 0~-WCI 6 was satisfactorily prepared using the method t-,/I r., ,'-I-" i'.…”