Size-Dependent Infrared Phonon Modes and Ferroelectric Phase Transition in BiFeO3 Nanoparticles
- University of Tennessee
- ORNL
- State University of New York, Stony Brook
- University of Tennessee, Knoxville (UTK)
One emergent property of ferroelectric nanoparticles is the sized-induced structural distortion to a high-symmetry paraelectric phase at small particle sizes. Finite length scale effects can thus be advantageously employed to elucidate ferroelectric transition mechanisms. In this work, we combine infrared spectroscopy with group theory and lattice dynamics calculations to reveal the displacive nature of the ferroelectric transition in BiFeO3, a room temperature multiferroic. Systematic intensity and frequency trends in selected vibrational modes show that the paraelectric phase is Pm3 m and the lowest frequency A1 feature is the soft mode that drives the first order transition. Finite length scale effects are also evident in the electronic structure with a red-shifted band gap in nanoscale BiFeO3 compared with that of the rhombohedral film, a result that can impact the development of ferroelectric photovoltaics and oxide-based electronics. Taken together, these findings demonstrate the foundational importance of size effects for enhancing the rich functionality and broad utility of transition metal oxides.
- Research Organization:
- Oak Ridge National Laboratory (ORNL)
- Sponsoring Organization:
- ORNL LDRD Director's R&D
- DOE Contract Number:
- AC05-00OR22725
- OSTI ID:
- 992558
- Journal Information:
- Nano Letters, Journal Name: Nano Letters Journal Issue: 11 Vol. 10; ISSN 1530-6992; ISSN 1530-6984
- Country of Publication:
- United States
- Language:
- English
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Size-Dependent Infrared Phonon Modes and Ferroelectric Phase Transition in BiFe03 Nanoparticles
Journal Article
·
Mon Nov 01 00:00:00 EDT 2010
· Nano Letters
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OSTI ID:1020848