Determination of the crystal structure of yttrium orthoferrite and refinement of gadolinium orthoferrite

Abstract : The crystal structure of yttrium orthoferrite has been determined from full three-dimensional counter data and refined in the space group Pbnm by least squares to an accuracy of about .001 and .01A in positional parameters of Y(3+) and O(2-) respectively. Parameters are compared with those of GdFeO3, derived by least squares refinement of Geller's intensity data. It is found that the distortions from the ideal perovskite lattice hardly affect the octahedral environment of the Fe(3+) ion, which makes it possible to predict Fe(3+)-O(2-)-Fe(3+) angles in other distorted perovskite structures of known cell dimensions. Refinement in the alternative non-centric space group Pbn2 sub 1, shows small possibly real deviations from a centric structure. (Author)