β-Fe2O3, a New Structural Form of Iron (III) Oxide

THE cigar shaped crystals of β-iron (III) oxide hydroxide produced by hydrolysis of a dilute solution of iron (III) chloride are remarkably porous. Channels which are virtually uniform in diameter throughout their length occur at regular intervals and run parallel to the long axis (c axis) of the crystal1. These channels are much larger (diameter 28.4 A s.d. 7.0 A) than the structural tunnels (cross section 5 × 5 A) of the hollandite structure of this compound. Although X-ray powder diffraction showed that the crystals possessed the hollandite structure, the presence of the large channels could not be detected because the channels, although regularly placed, are too widely spaced (60 A intervals) and too few to register any diffraction effects.