A-site strontium doping effects on structure, magnetic, and photovoltaic properties of (Bi1-xSrx)FeO3-delta multiferroic ceramics

초록

Raman spectroscopy, X-ray diffraction (XRD), magnetization hysteresis loop, synchrotron X-ray absorption spectroscopy, and photovoltaic effects have been measured in (Bi1-xSrx)FeO3-delta (BF0100xSr) ceramics for x=0.0, 0.05, 0.10, and 0.15. Raman spectra and XRD reveal a rhombohedral R3c structure in all compounds. A-site Sr2+ doping increases fluctuations in cation-site occupancy and causes broadening in Raman modes. BFO15Sr exhibits a strong ferromagnetic feature due to reduction of Fe-O-Fe bond angle evidenced by the extended synchrotron X-ray absorption fine structure. The heterostructure of indium tin oxide (ITO) film/(Bi1-xSrx)FeO3-delta ceramic/Au film exhibit clear photovoltaic (PV) responses under blue illumination of lambda=405 nm. The maximal power-conversion efficiency and external quantum efficiency in ITO/BFO5Sr/Au are about 0.004% and 0.2%, respectively. A model based on optically excited charges in the depletion region between ITO and (Bi1-xSrx)FeO3-delta can well describe open-circuit voltage and short-circuit current as a function of illumination intensity. (C) 2015 Elsevier Ltd and Techna Group S.r.l. All rights reserved.

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