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arXiv · 1609.00859

Soft Phonon Mode Dynamics in Aurivillius Type Structures

Deepam Maurya·Ali Charkhesht·Sanjeev K. Nayak·Fu-Chang Sun·Deepu George·Abhijit Pramanick·Min-Gyu Kang·Hyun-Cheol Song·Marshall M. Alexander·Djamila Lou·Giti A. Khodaparast·S. Pamir Alpay·N. Q. Vinh·Shashank Priya
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Abstract

We report the dynamics of soft phonon modes and their role towards the various structural transformations in Aurivillius materials by employing terahertz frequency-domain spectroscopy, atomic pair distribution function analysis, and first-principles calculations. We have chosen Bi4Ti3O12 as a model system and identified soft phonon modes associated with the paraelectric tetragonal to the ferroelectric monoclinic transition. Three soft phonon modes have been discovered which exhibit a strong temperature dependence. We have determined that the anharmonicity in Bi-O bonds plays a significant role in phonon softening and that Bi cations play an important role in the emergence of ferroelectricity.

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Deepam Maurya, Ali Charkhesht, Sanjeev K. Nayak, Fu-Chang Sun, Deepu George, Abhijit Pramanick, Min-Gyu Kang, Hyun-Cheol Song, Marshall M. Alexander, Djamila Lou, Giti A. Khodaparast, S. Pamir Alpay, N. Q. Vinh, Shashank Priya. 2016-09-03. Soft Phonon Mode Dynamics in Aurivillius Type Structures. https://doi.org/10.1103/physrevb.96.134114

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