期刊
NANO LETTERS
卷 10, 期 11, 页码 4526-4532出版社
AMER CHEMICAL SOC
DOI: 10.1021/nl102470f
关键词
Bismuth ferrite; ferroelectric transition; finite size effects; soft mode; lattice dynamics; photovoltaics
类别
资金
- Materials Science Division, Basic Energy Sciences, U.S. Department of Energy [DE-FG02-01ER45885, DE-AC02-98CH10886]
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 cars 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 Pm (3) over barm and the lowest frequency A(1) feature is the soft mode that drives Me 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.
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