Journal ArticleDOI
Wide-range tunable bandgap in Bi1−xCaxFe1−yTiyO3−δ nanoparticles via oxygen vacancy induced structural modulations at room temperature
Pavana S. V. Mocherla,Sanjeev Gautam,Keun Hwa Chae,M. S. Ramachandra Rao,Chandran Sudakar +4 more
- Vol. 2, Iss: 9, pp 095012
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TLDR
In this article, the authors demonstrate that oxygen vacancies produced by aliovalent (Ca2+) doping in BiFeO3 (BCFO) and associated structural changes due to VO ordering result in systematic alteration of the bandgap (Eg) over a wide range from 1.5 eV to 2.3 eV.Abstract:
We demonstrate that oxygen vacancies (VO) produced by aliovalent (Ca2+) doping in BiFeO3 (BCFO) and associated structural changes due to VO ordering result in systematic alteration of the bandgap (Eg) over a wide range from 1.5 eV to 2.3 eV. By contrast, the change in the bandgap of a Ca2+ and Ti4+ co-doped BiFeO3 (BCFTO) system, wherein the VO formation is suppressed, is negligible. These contrastive results strongly confirm the role of oxygen vacancies in altering the bandgap of BCFO. Irrespective of doping, microstrain, which is found to be large (0.3 to 1.2%) below a critical size (dc ~ 60 nm) also produces a small, yet linear change in the bandgap (Eg from 2.0 to 2.3 eV). The cubic phase stabilizes gradually in BCFO for x > 0.1 through an orthorhombic phase (for 0.05 0.1 in BCFTO. This change in BCFO at 300 K suggests a high-pressure-like (or high-temperature-like) effect of the oxygen vacancies and dopants on the structure. Systematic variations in the relative intensities and peak positions of Fe d–d transitions in BCFO reveal the local changes in Fe–O–Fe coordination. These results along with XANES and HRTEM studies substantiate the observed structural changes.read more
Citations
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Journal ArticleDOI
Characterization and photocatalytic activity of Y-doped BiFeO3 ceramics prepared by solid-state reaction method
TL;DR: In this article, a singe phase bismuth ferrite doped by yttrium (Bi1−xYxFeO3, x = 0, 0.05, 1, 0., 0.15, 1.2 and 0.25) was synthesized by solid-state reaction followed by sintering.
Journal ArticleDOI
Strain induced magnetic anisotropy and 3d 7 ions effect in CoFe 2 O 4 nanoplatelets
TL;DR: In this article, the compressive microstrain of 0.024 and 0.016 was estimated for CoFe2O4 samples H120 and H180 respectively using Williamson-Hall plot analysis assuming uniform deformation model.
Journal ArticleDOI
Chemical pressure induced red shift in band gap and d-d transition energies in Sr doped BiFeO3
TL;DR: In this article, the optical response of multiferroic Bi1−xSrxFeO3 (0,≤,x,≤ 0.45) samples is studied in the spectral range from 1 eV to 4 eV.
Journal ArticleDOI
Maximizing Short Circuit Current Density and Open Circuit Voltage in Oxygen Vacancy-Controlled Bi1-xCaxFe1-yTiyO3-δ Thin-Film Solar Cells.
TL;DR: This work demonstrates oxygen vacancies (VO), present within the lattice and at grain boundary (GB), can explicitly be controlled to achieve high JSC and VOC simultaneously and demonstrates the efficiency ~ 0.22 % can be achieved in solid state BFO solar cells under AM 1.5 one Sun illumination.
Journal ArticleDOI
Photoconductivity induced by nanoparticle segregated grain-boundary in spark plasma sintered BiFeO3
TL;DR: In this article, photo-response of nanoparticle-segregated grain boundary (BFO-AP) and clean grain boundary(BFO -AA) samples was investigated on spark plasma sintered BiFeO3 samples with two contrasting morphologies.
References
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L2,3 x-ray-absorption edges of d0 compounds: K+, Ca2+, Sc3+, and Ti4+ in Oh (octahedral) symmetry.
TL;DR: Les limites d'absorption des rayons X L 2,3 des composes 3d 0 sont calculees a l'aide de l'excitation 2p 6 3d0 a 2p 5 3d 1 , en incluant le champ cristalin.
Journal ArticleDOI
Photovoltaic effects in BiFeO3
S. Y. Yang,Lane W. Martin,Byrnes Steven J,Byrnes Steven J,Thomas E. Conry,Thomas E. Conry,S. R. Basu,D. Paran,Lothar A. Reichertz,Jon F. Ihlefeld,Carolina Adamo,A. Melville,Ying-Hao Chu,Chan-Ho Yang,Janice L. Musfeldt,D. G. Schlom,Joel W. Ager,Ramamoorthy Ramesh,Ramamoorthy Ramesh +18 more
TL;DR: In this article, the photovoltaic effect in ferroelectric BiFeO3 thin films was reported and the all-oxide heterostructures with SrRuO3 bottom and tin doped indium oxide top electrodes were characterized by open-circuit voltages ∼08-09V and external quantum efficiencies up to ∼10% when illuminated with the appropriate light.
Journal ArticleDOI
Fluorographene: a wide bandgap semiconductor with ultraviolet luminescence.
Ki-Joon Jeon,Zonghoon Lee,Elad Pollak,Luca Moreschini,Aaron Bostwick,Cheol-Min Park,Rueben J. Mendelsberg,Velimir Radmilovic,Robert Kostecki,Thomas J. Richardson,Eli Rotenberg +10 more
TL;DR: It is shown that treatment of graphene with xenon difluoride produces a partially fluorinated graphene (fluorographene) with covalent C-F bonding and local sp(3)-carbon hybridization, suggesting the use of fluorographane as a new, readily prepared material for electronic, optoelectronic applications, and energy harvesting applications.
Journal ArticleDOI
Band gap and Schottky barrier heights of multiferroic BiFeO3
Stewart J. Clark,John Robertson +1 more
TL;DR: In this article, the Schottky barrier height on Pt or SrRuO3 is calculated in the metal induced gap state model to be over 0.9eV and the band gap is calculated by the density functional based screened exchange method to be 2.8eV, similar to experiment.
Journal ArticleDOI
Efficient photovoltaic current generation at ferroelectric domain walls.
Jan Seidel,Jan Seidel,Deyi Fu,Deyi Fu,S. Y. Yang,Esther Alarcon-Llado,Esther Alarcon-Llado,Junqiao Wu,Junqiao Wu,Ramamoorthy Ramesh,Ramamoorthy Ramesh,Joel W. Ager +11 more
TL;DR: The mechanism of a newly observed photovoltaic effect which occurs in ferroelectrics with periodic domain structures, found in BiFeO(3) films, is elucidated and should occur in any system with a similar periodic potential.