Tailoring microstructure and photovoltaic effect in multiferroic Nd-substituted BiFeO3 ceramics by processing atmosphere modification
Schmidt, V. Hugo
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This study highlights significant effects of processing atmosphere ratio (O2/N2) on microstructure, impurity phases, atomic hybridization, band gap, and photovoltaic properties in (Bi0.93Nd0.07)FeO3 (BFO7Nd) ceramics. A Rietveld-refinement analysis indicates increased oxygen and bismuth vacancies in the specimens processed in the O2-rich atmosphere (hereafter called O2-rich-atmosphere specimens). In the matrix containing mainly Fe3+ ions, Fe4+ cations were identified with O2 concentration decreasing in the atmosphere by Fe K/L-edges synchrotron X-ray absorption. Oxygen K-edge absorption reveals reduced hybridizations of the O 2p–Fe 3d and the O 2p–Bi 6sp orbitals in the O2-rich-atmosphere specimens. Photovoltaic effects in the ITO/BFO7Nd/Au heterostructures under near-ultraviolet irradiation (λ = 405 nm) exhibit strong dependences on O2/N2 ratio. A p-n-junction model was used to describe open-circuit voltage and short-circuit current density as functions of irradiation intensity. The calculated carrier densities (in BFO7Nd ceramics) and p-n-junction widths (in the dark) are ∼1023 m−3 and a few hundred nanometers, respectively.
Tu, Chi-Shun, Pin-Yi Chen, Cheng-Sao Chen, Chun-Yen Lin, and V. Hugo Schmidt. "Tailoring microstructure and photovoltaic effect in multiferroic Nd-substituted BiFeO3 ceramics by processing atmosphere modification." Journal of the European Ceramic Society, 38 no. 4 (November 2017): 1389-1398. DOI: 10.1016/j.jeurceramsoc.2017.11.025.