论文标题
压力诱导的相变和电子特性CD2V2O7
Pressure-induced phase transitions and electronic properties Cd2V2O7
论文作者
论文摘要
我们报告了在高压条件下CD2V2O7的结构和电子特性的密度功能理论研究。该计算是通过使用晶体程序的第一原则计算进行的。提出了两个结构相变的发生在0.3和10.9 GPa时。报道了不同高压相的晶体结构。有趣的是，预测在压缩下可以稳定下立方的pyrochlore型结构。这两个相转换涉及CD和V的配位多面体的实质变化。我们还确定了CD2V2O7的三个多晶型物的压缩性和室温方程。根据我们的系统电子带构建计算，在环境条件下，CD2V2O7是一种间接的宽带隙材料，带隙能量为4.39 eV。另外，已经确定了带隙的压力依赖性。特别是，我们发现在第二阶段过渡后，频带隙突然降低到2.56 eV的值。
We report a density-functional theory study of the structural and electronic properties of Cd2V2O7 under high-pressure conditions. The calculations have been performed by using first-principle calculations with the CRYSTAL program. The occurrence of two structural phase transitions, at 0.3 and 10.9 GPa, is proposed. The crystal structure of the different high-pressure phases is reported. Interestingly a cubic pyrochlore-type structure is predicted to stabilize under compression. The two phase transitions involve substantial changes in the coordination polyhedra of Cd and V. We have also determined the compressibility and room-temperature equation of state of the three polymorphs of Cd2V2O7. According to our systematic electronic band-structure calculations, at ambient conditions Cd2V2O7 is an indirect wide band-gap material with a band-gap energy of 4.39 eV. In addition, the pressure dependence of the band gap has been determined. In particular, we have found that after the second phase transition the band gap decreases abruptly to a value of 2.56 eV.
