科研之友
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摘要
AgNbO3 has been reported to undergo an antiferroelectric-ferroelectric phase transition between two orthorhombic phases (labeled M-2 and M-1) on cooling below similar to 340 K. However, the phase transition mechanism is still not well understood, with different space groups proposed for the structure on the basis of different experimental techniques. Here, we report the first-principles calculations of low-temperature phases of AgNbO3 using the projector augmented wave method based on the density functional theory. The calculated phonon dispersion curve for the antiferroelectric Pbcm structure shows that no soft mode is evident over all wave vectors, indicating that the structure is dynamically stable. The M-2-M-1 transition of AgNbO3 thus cannot be explained on the basis of these results. Further calculations are needed to uncover the precise phase transition mechanism for this compound.
- 出版日期2012-9
