STRUCTURAL AND MAGNETIC STUDIES ON PRBA2FE3O8

It is known that Fe moments order antiferromagnetically with Neel temp erature, T-No above 700 K in RBa(2)Fe(3)O(7-delta) with R = Y and Eu, and Pr moments order antiferromagnetically in PrBa2Cu3O7-delta, with T -N of 17 K. We have synthesized PrBa2Fe3O8 to study the ordering of Pr and Fe moments. From X-ray and neutron diffraction studies, this comp ound is found to crystallize in the tetragonal structure (space group P4/mmm). Fe-57 Mossbauer studies show a complex hyperfine split patter n at 77 K, but a doublet superimposed on a six-line pattern at 300 K i mplying that some of the Fe moments order magnetically between 77 and 300 K while others may have ordering temperature of more than 300 K. M agnetization measurements reveal discontinuities in the susceptibility data around 80 and 20 K, probably an indication of magnetic ordering of the Fe and Pr moments. Neutron diffraction studies at 300 K suggest the presence of additional oxygen in the Pr plane and a magnetic stru cture very different from that of YBa2Fe3O8.