科研之友
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摘要
The structural instability of Cd2Ta2O7 (CTO) is studied by first-principles calculations. All of the zone-center phonons for the cubic CTO with symmetry have real frequencies. However, one soft mode at the X-point with an imaginary frequency of 17.5cm(-1) is found. By freezing in this soft mode we obtain an energetically favorable structure with Pnma symmetry. The Pnma phase is centrosymmetric and thus is not ferroelectric. Detailed analysis indicates that the Pnma phase CTO is antiferroelectric. Thus our results approve that the phase transition reported experimentally is an antiferroelectric transition.
- 出版日期2016
- 单位昆明理工大学
