First-principles investigations of ferroelectricity and piezoelectricity in BaTiO3/PbTiO3 superlattices
First-principles investigations of ferroelectricity and piezoelectricity in BaTiO3/PbTiO3 superlattices
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BaTiO3/PbTiO3 超晶格铁电性和压电性的第一性原理研究
DOI：
10.1103/physrevb.85.054108
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发表时间：
2012-02-13
影响因子：
3.7
通讯作者：
Wu，Zhigang
中科院分区：
文献类型：
--
作者：
Duan，Yifeng;Tang，Gang;Wu，Zhigang
采用第一性原理计算方法研究了四元BaTiO 3/PbTiO 3（BPT）短周期超晶格的铁电性和压电性的压力依赖性。我们的研究结果表明，随着施加的压力增加，BPT超晶格首先成为顺电在低压，然后转移到另一个铁电相在更高的压力。此外，预测接近相变区域的压电性的大增强，类似于先前在PbTiO 3中预测的。将BPT超晶格与体相BaTiO 3和PbTiO 3进行比较，发现BPT超晶格在高压下的第一次相变与体相BaTiO 3的行为非常相似，但其相变压力和零压自发极化比PbTiO 3低得多，尽管BPT具有相同数量的BaTiO 3和PbTiO 3层。然而，对于第二转变，BPT具有接近BaTiO 3和PbTiO 3的平均转变压力，并且所有三种材料具有相似的压力诱导极化。此外，我们的计算表明，在压电的巨大增强是强烈相关的相变时，大的原子位移可以由小的外部应变，但极化旋转是不是一个必要条件。
The pressure dependence of ferroelectricity and piezoelectricity of a tetragonal BaTiO3/PbTiO3 (BPT) shortperiod superlattice is investigated using first-principles calculations. Our results suggest that, as the applied pressure increases, the BPT superlattice first becomes paraelectric at low pressures and then transfers to another ferroelectric phase at much higher pressures. Furthermore, a large enhancement of piezoelectricity close to the phase-transition regions is predicted, similar to that previously predicted in PbTiO3. Comparing the BPT superlattice with bulk BaTiO3 and PbTiO3, we find that the BPT superlattice behaves very similarly to bulk BaTiO3 under high pressures for the first transition, while it has much lower transition pressure and zero-pressure spontaneous polarization than those for PbTiO3, although BPT has an equal number of BaTiO3 and PbTiO3 layers. However, for the second transition, BPT has a transition pressure close to the average of those for BaTiO3 and PbTiO3, and all three materials have similar pressure-induced polarization. Furthermore, our calculations indicate that the colossal enhancement in piezoelectricity is strongly correlated to phase transition when large atomic displacements can be generated by small external strain, but polarization rotation is not a necessary condition.