Neutron diffraction and Mossbauer studies of the La0.67Ba0.33Mn0.9957Fe0.01O3

The perovskite (La0.67Ba0.33Mn0.99Fe0.01O3)-Fe-57 was prepared by wet chemical solution process at 1200 degreesC for 3 h. Magnetic properties of (La0.67Ba0.33Mn0.99Fe0.01O3)-Fe-57 were studied using X-ray diffraction, Rutherford backscattering spectroscopy (RBS), neutron diffraction, Mossbauer spectroscopy, vibrating sample magnetometry, and magnetoresistance measurements. The polycrystalline (La0.67Ba0.33Mn0.99Fe0.01O3)-Fe-57 had a space group Pnma of orthorhombic perovskite structure with lattice constants a(0) = 5.526 Angstrom, b(0) = 7.830 Angstrom, and c(0) = 5.540 A, respectively. A chemical composition was confirmed to be stoichiometric by RBS. The maximum magnetoresistance ratio (Deltarho/rho(0)) was observed at 281 K, with a magnitude of 9.5% in 1 Tesla. The Curie temperature (T-C) was determined to be 3 45 K. Mossbauer spectra of (La0.67Ba0.33Mn0.99Fe0.01O3)-Fe-57 were taken at various temperatures ranging from 15 to 400 K. Below 77 K, two magnetic phases were increased and showed two sharp sextets of spectra. The magnetic hyperfine fields of outer (51%) and inner (49%) subspectrum were H-hf = 530 and 480 kOe, respectively. These unusual phenomena provide direct evidence of the two-magnetic phase character of the metallic state in the mixed valence of (La0.67Ba0.33Mn0.99Fe0.01O3)-Fe-57 powder. The outer sextet of Mossbauer spectra rapidly collapsed to paramagnetic phase With increasing temperature.