Zhi Wang¹, Jinming Cao¹, Zhonglei Liu¹, Yuhong Zhao^1,2,3,*

CMC-Computers, Materials & Continua, Vol.81, No.1, pp. 213-228, 2024, DOI:10.32604/cmc.2024.055169 - 15 October 2024

Abstract Recent years, the polarization response of ferroelectrics has been entirely studied. However, it is found that the polarization may disappear gradually with the continually applied of electric field. In this paper, taking K_0.48Na_0.52NbO₃(KNN) as an example, it was demonstrated that the residual polarization began to decrease when the electric field frequency increased to a certain extent using a phase-field methods. The results showed that the content of out-of-plane domains increased first and then decreased with the increase of applied electric field frequency, the maximum polarization disappeared at high frequencies, and the hysteresis loop became elliptical. In More >

Mustafa Uludoğan¹, D. Paula Guarin¹, Zully E. Gomez¹, Tahir Cagin¹, William A. Goddard III²

CMES-Computer Modeling in Engineering & Sciences, Vol.24, No.2&3, pp. 215-238, 2008, DOI:10.3970/cmes.2008.024.215

Abstract Aiming at a presentation of the utility of the state of art of first-principles methods (PBE flavor of Density Functional Theory, DFT) in the area of materials science and engineering, we present our studies of the equation of state and ferroelectric-paraelectricphase transition in several ferroelectric systems, including BaTiO₃, PbTiO₃, SrTiO₃, AgNbO₃, Pb_xBa_1-xTiO₃ and Sr_xBa_1-xTiO₃. We also report the Born effective charges, optical dielectric constant, and phonon dispersion relation properties from Density Functional Perturbation Theory. Computed results are compared with other theoretical results (which were mostly on BaTiO₃, PbTiO₃, cubic SrTiO₃ using various approaches, as well as experiments. The studies on More >