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
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 Article
Band Gap Engineering via Local Environment in Complex Oxides
TL;DR: In this paper, the authors examined the effect of B-site ordering, lattice strain, cation identity, and oxygen octahedral cage tilts on the band-structure engineering of extremely tetragonal ferroelectric perovskites (ABO3).
Journal ArticleDOI
High temperature magnetic studies on Bi1-xCaxFe1−yTiyO3-δ nanoparticles: Observation of Hopkinson-like effect above TN
Pavana S. V. Mocherla,D. Prabhu,M.B. Sahana,Neha Hebalkar,Raghavan Gopalan,M. S. Ramachandra Rao,Chandran Sudakar +6 more
TL;DR: In this article, the magnetic properties of BCFO and BCFTO nanoparticles are studied across a wide range of temperatures (20, K to 960, K) for different Ca (and Ti) concentrations.
Journal ArticleDOI
Coexistence of large negative and positive magnetodielectric response in Bi 1 − x Ca x Fe 1 − y Ti y O 3 − δ nanoparticle ceramics
Subhajit Nandy,Pavana S. V. Mocherla,Ehab Abdelhamid,Boris Nadgorny,R. Naik,Chandran Sudakar +5 more
TL;DR: In this paper, the magnetic properties of air-annealed nanoparticle ceramics made by spark plasma sintering process are investigated as a function of temperature, showing that positive and negative magnetodielectric (MD) properties of nanoparticles exhibit a strong coupling between the magnetic and dielectric properties.
Journal ArticleDOI
Influence of preparation method on phase formation, structural and magnetic properties of BiFeO3
Journal ArticleDOI
Influence of chemical solution growth and vacuum annealing on the properties of (100) pseudocubic oriented BiFeO3 thin films
Subhajit Nandy,Chandran Sudakar +1 more
TL;DR: In this paper, the authors report on the oriented growth of BFO thin films using a facile metal-organic chemical solution deposition on sapphire (0001) to yield highly oriented thin films along (100)pc planes.
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