STRUCTURAL AND UNIQUE MAGNETIC-PROPERTIES OF PRBA2FE3O8

Tetragonal PrBa2Fe3O8 exhibits a unique magnetic behavior and behaves differently from both PrBa2Cu3O7 and all RBa(2)Fe(3)O(8) materials. Ma gnetic-susceptibility study reveals two anomalies at 23 and 55 K which are sensitive to oxygen concentration, but no specific heat anomaly w as observed at either temperature. Mossbauer studies reveal two inequi valent iron sites, which order antiferromagnetically at approximate to 230 K, in contrast to 670 K in RBa(2)Fe(3)O(8). X-ray absorption spec tra indicate that Pr is trivalent. In contrast to PrBa2Cu3O7 [T-N(Pr)= 17 K] Pr in PrBa2Fe3O8 does not order magnetically. The anomalies at 2 3 and 55 K are probably related to spin reorientation of Fe moments.