Tunable Bandgap in BiFeO₃ Nanoparticles: The Role of Microstrain and Oxygen Defects

Authors

Pavana S. V. Mocherla, Indian Institute of Technology - Madras
C. Karthik, Boise State UniversityFollow
R. Ubic, Boise State UniversityFollow
M. S. Ramachandra Rao, Indian Institute of Technology - Madras

Document Type

Article

Publication Date

7-8-2013

Abstract

We demonstrate a tunable bandgap from 2.32 eV to 2.09 eV in phase-pure BiFeO₃ by controlling the particle size from 65 nm to 5 nm. Defect states due to oxygen and microstrain show a strong dependence on BiFeO₃ particle size and have a significant effect on the shape of absorbance curves. Oxygen-defect induced microstrain and undercoordinated oxygen on the surface of BiFeO₃ nanoparticles are demonstrated via HRTEM and XPS studies. Microstrain in the lattice leads to the reduction in rhombohedral distortion of BiFeO₃ for particle sizes below 30 nm. The decrease in band gap with decreasing particle size is attributed to the competing effects of microstrain, oxygen defects, and Coulombic interactions.

Publication Information

Mocherla, Pavana S. V.; Karthik, C.; Ubic, R.; and Rao, M. S. Ramachandra. (2013). "Tunable Bandgap in BiFeO₃ Nanoparticles: The Role of Microstrain and Oxygen Defects". Applied Physics Letters, 103(2), 022910-1-022910-5. https://doi.org/10.1063/1.4813539