Soft X-ray absorption (XAS), transmission electron spectroscopy (TEM), Raman spectroscopy, and synchrotron XRD have been studied in B-site 0-2 mol% manganese (Mn) doped (Bi 0.5 Na 0.5) 0.925 Ba 0.075 TiO 3 (BN7.5BT) relaxor ferroelectric ceramics. High-resolution synchrotron XRD and TEM reveal two phase coexistence of rhombohedral R3c and tetragonal P4bm structures in 0 and 0.2%, and an orthorhombic structure in 1 and 2% Mn-doped BN7.5BT at room temperature. Raman spectra of 0% Mn reveal structural transition from two phase coexistence to tetragonal phase near 190 o C with a softening anomaly, while 0.2-2% Mn-doped BN7.5BT show softening behavior near 290 o C upon heating. Raman spectra and synchrotron XRD indicate that Mn doping can enhance structural thermal stability in BN7.5BT ceramics.

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This work reports enhanced photovoltaic (PV) responses of (Bi 1 − x Sm x)FeO 3 (x = 0.0, 0.05, 0.10) ceramics (BFO100xSm) with ITO film under near-ultraviolet irradiation (= 405 nm). The ceramics were characterized by micro-Raman scattering, high-resolution transmission electron microscopy, and synchrotron X-ray absorption spectroscopy (XAS). A rhombohedral R3c symmetry with tilted FeO 6 octahedra has been confirmed. The Fe K-edge absorption spectra reveal a slight shift toward higher energy as A-site Sm 3+ substitution increases. The oxygen K-edge XAS reveals an enhancement of hybridization between the O 2p and unoccupied Fe 3d states due to Sm doping. The optical band gaps are in the range of 2.15-2.24 eV. The maximal PV power-conversion and external quantum efficiencies respectively reach 0.37% and 4.1% in the ITO/BFO5Sm/Au heterostructure. The PV responses can be described quantitatively by a p-n-junctionlike model. The domain structures and hybridization between the O 2p and Fe 3d states play important roles for the PV responses.