LOWER HALIDES OF HAFNIUM . A NONSTOICHIOMETRIC HAFNIUM TRIIODIDE PHASE

A hafnium iodide phase of the composition HfI3.2-3.3 which is free of unreacted metal is obtained by the reaction of liquid HfI4 with metal foil (600 ppm of Zr) in a sealed tantalum container at 500-550°. The lower composition limit established from equilibration with separate metal powder is HfI3.00 at 425-575°; the phase in equilibrium with HfI4(1) varies from HfI3.46 at 475° to HfI3.20 at 550°. Neither equilibration of HfI4 or HfI3 with metal at up to 1000° nor disproportionation of HfI3 under high vacuum gives any indication of the existence of still lower iodide, specifically HfI2. X-Ray powder data indicate that the a and c dimensions of the previously suggested hexagonal unit cell2 should probably be doubled and quadrupled, respectively. The composition HfI3.35 shows a small temperature-independent paramagnetism corresponding to a μeffvalue of 0.68 at 300°K; the susceptibilities are considerably smaller than reported earlier3 for impure samples. © 1969, American Chemical Society. All rights reserved.