THE STRUCTURAL STUDY OF SR4FE6O13 USING A WEISSENBERG TECHNIQUE AND SYNCHROTRON-RADIATION - UNUSUAL IONIC-RADII OF 5-COORDINATED FE3+ IONS

The structure of Sr4Fe6O13 is orthorhombic, space group Iba2, with uni t cell dimensions a = 11.278(3) Angstrom, b = 18.953(6) Angstrom, c = 5.546(3) Angstrom, Z = 4. The crystal structure was refined by full-ma trix least-squares to R = 0.010 using 301 reflections measured with an imaging plate using a Weissenberg camera and monochromatized synchrot ron radiation of wavelength 1.000 Angstrom. The result is essentially the same with the previously reported structure (Yoshiasa, Ueno, Kanam aru, Horiuchi, 1986) but has yielded some details of the structure in which Fe-O bondings are involved. The polyhedral distortions and ionic radii for the five coordinated Fe3+ ions in the structure have been d iscussed in comparison with those of related structures.