Chin. Phys. Lett.  2016, Vol. 33 Issue (04): 047701    DOI: 10.1088/0256-307X/33/4/047701
 CONDENSED MATTER: ELECTRONIC STRUCTURE, ELECTRICAL, MAGNETIC, AND OPTICAL PROPERTIES |
First-Principles Investigations of Pb$_{0.5}$Ba$_{0.5}$TiO$_3$ Alloys Based on Structure Predictions
Hong-Bo Wu, Yi-Feng Duan**, Chang-Ming Zhao, Kun Liu, Li-Xia Qin
Department of Physics, China University of Mining and Technology, Xuzhou 221116
Hong-Bo Wu, Yi-Feng Duan, Chang-Ming Zhao et al  2016 Chin. Phys. Lett. 33 047701
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Abstract Crystal structure predictions of Pb$_{0.5}$Ba$_{0.5}$TiO$_3$ alloys under different pressures are performed based on the particle swarming optimization algorithm. The predicted stable ground-state and high-pressure phases are tetragonal ferroelectric ($I4mm$) and cubic para-electric ($Fm\bar{3}m$), respectively, whose structural details have not been reported. The pressure-induced colossal enhancements in piezoelectric response are associated with the mechanical and dynamical instabilities instead of polarization rotation. The band gap of the tetragonal phase is indirect and that of the cubic phase is always direct. As pressure increases, the alloy displays the similar band-gap behaviors to PbTiO$_3$, while different from BaTiO$_3$, which is attributed to the different orbital contributions to the valence bands. Our calculated results are in good agreement with the available data.
Received: 03 January 2016      Published: 29 April 2016
 PACS: 77.80.B- (Phase transitions and Curie point) 62.50.-p (High-pressure effects in solids and liquids) 63.20.D- (Phonon states and bands, normal modes, and phonon dispersion)
 TRENDMD: URL: http://cpl.iphy.ac.cn/10.1088/0256-307X/33/4/047701       OR      http://cpl.iphy.ac.cn/Y2016/V33/I04/047701