ISSN:
1573-4803
Source:
Springer Online Journal Archives 1860-2000
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
Notes:
Abstract A new isomorphic analogue ofβ″-alumina, a potassium-free Na-ferrite (Na2O · ∼5 (Al0.10Fe1.90)O3, referred to as Naβ″-ferrite), has been synthesized and is characterized using X-ray powder and single crystal diffraction, wet chemical analysis, and transmission electron microscopy (TEM). In addition, Naβ″-aluminate-gallate-ferrate phases were also successfully synthesized, but were not characterized in detail. Naβ″-ferrite grew in a slowly cooling melt or partial melt from 1250° C in air using Na2CO3 and Fe3O4 (magnetite) as starting materials. The compound was also synthesized usingα-Fe2O3 instead of Fe3O4 under the same conditions, but its abundance was much less andα-Fe2O3 and NaFeO2 were the dominant phases. The new material (cell dimensionsa = 0.5955,c = 3.5623 nm) is reversibly hygroscopic, andc increases 2% after hydration. TEM images dearly show the 1.19 nm lattice spacing corresponding to the ionic conduction planes, and these planes are observed to be both straight and curled. The origin of the curled lattice planes, the existence of which is also evident in the single crystal precession photographs, is not clear, although we believe it may involve a structural misfit between the ferric oxide spineI block and soda layer.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01145532
