Phase studies in the uranium-hafnium system

Abstract

The lattice constants are a = 10.759 A. and c = 5.656 A. (4, 10). The exact space group and precise atomic positions have been the subjects of considerable debate, the status of which has been discussed by Tucker et al. (11). The high temperature, gamma modification of uranium was established as body-centered cubic with two atoms per unit cell by "Tilson and Bundle (12). The lattice constant at 800°C.

High temperature allotropy of the rare-earth elements

“…The transformation of the close packed structures to the bcc structures in the rare earths and yttrium are accompanied by abrupt changes in the electrical resistivity, as observed in this work and elsewhere (14,60). Such transformations in zirconium and hafnium are accompanied by similar changes in electrical resistivity (108,109). The changes in electrical resistivity of terbium at 1316°C and those of dysprosium and holmium have the characteristics of a close-packed to bcc transformation.…”