Wide-range tunable bandgap in Bi1−xCaxFe1−yTiyO3−δ nanoparticles via oxygen vacancy induced structural modulations at room temperature
作者：
DOI: 10.1088/2053-1591/2/9/095012
关键词: XANES 、 Band gap 、 Phase (matter) 、 Dopant 、 Oxygen 、 Orthorhombic crystal system 、 High-resolution transmission electron microscopy 、 Crystallography 、 Materials science 、 Doping
摘要: We demonstrate that oxygen vacancies (VO) produced by aliovalent (Ca2+) doping in BiFeO3 (BCFO) and associated structural changes due to VO ordering result systematic alteration of the bandgap (Eg) over a wide range from 1.5 eV 2.3 eV. By contrast, change Ca2+ Ti4+ co-doped (BCFTO) system, wherein formation is suppressed, negligible. These contrastive results strongly confirm role altering BCFO. Irrespective doping, microstrain, which found be large (0.3 1.2%) below critical size (dc ~ 60 nm) also produces small, yet linear (Eg 2.0 eV). The cubic phase stabilizes gradually BCFO for x > 0.1 through an orthorhombic (for 0.05 BCFTO. This at 300 K suggests high-pressure-like (or high-temperature-like) effect dopants on structure. Systematic variations relative intensities peak positions Fe d–d transitions reveal local Fe–O–Fe coordination. along with XANES HRTEM studies substantiate observed changes.
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