Magnetization, phonon, and X-ray edge absorption in barium doped BiFeO3 ceramics


Magnetization hysteresis loops, dc and ac magnetic susceptibilities, and Raman vibrations have been characterized in (Bi1−xBax)FeO3−δ ceramics for x = 0.0, 0.05, 0.10, and 0.15 as functions of temperature. Ferromagnetic hysteresis loops were observed in Ba-doped compounds with increasing magnetization as Ba substitution increases. High-resolution synchrotron Fe K- and L2,3-edge X-ray absorptions reveal an Fe3+ valence and a modification of the Fe–O–Fe bond structure by the A-site Ba substitution. The oxygen K-edge X-ray absorption suggests that the hybridization of the O 2p and Fe 3d orbitals was reduced by the Ba2+ substitution. Field-cooled and zero-field-cooled magnetic susceptibilities reveal a spin-glass behavior, which was enhanced with increasing Ba substitution. Raman vibrations of the Bi- and Fe-sensitive E(2) and A1(1) modes reveal frequency softening and step-like anomalies in full-width-at-half-maximum in the vicinity of ~150–250 K, which were attributed to spin–phonon interaction while magnetic ordering transitions take place.




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