Probing localization effects in Li0.9Mo6O17 purple bronze:: An optical-properties investigation -: art. no. 085120
Probing localization effects in Li0.9Mo6O17 purple bronze:: An optical-properties investigation -: art. no. 085120
复制标题
DOI：
10.1103/physrevb.69.085120
复制
发表时间：
2004-02-01
影响因子：
3.7
通讯作者：
Brill, JW
中科院分区：
文献类型：
--
作者：
Choi, J;Musfeldt, JL;Brill, JW
我们报告的偏振反射率和光学电导率的准一维导体Li0.9Mo6O17作为温度的函数。该化合物显示出不寻常的（非德鲁德型）移动的载流子响应在低能量，部分屏蔽振动功能沿着高导电B轴。此外，我们观察到Mo d-->d跃迁接近0.42，0.57，和1.3 eV，和O p-->Mo d电荷转移带接近4 eV。在B轴附近，Li 0.9 Mo 6 O 17具有半导体性质，光学带隙为0.4 eV，电子结构与B轴相似。在这个方向上的振动模式的温度依赖性表明，晶格的Li0.9Mo6O17是不刚性的。然而，通过25 K的金属-绝缘体转变的晶格中没有观察到明显的变化。比较几种模型材料的X射线和红外数据，我们建立了一个上限的任何晶格畸变的大小在Li0.9Mo6O17。基于这些综合结果，我们认为，本地化效应占主导地位的这种材料的体积和微观特性。
We report the polarized reflectance and optical conductivity of the quasi-one-dimensional conductor Li0.9Mo6O17 as a function of temperature. The compound displays an unusual (non-Drude-type) mobile carrier response at low-energy, with partially screened vibrational features along the highly conducting b axis. In addition, we observe Mo d-->d transitions near 0.42, 0.57, and 1.3 eV, and an O p-->Mo d charge-transfer band near 4 eV. Perpendicular to the b axis, Li0.9Mo6O17 exhibits semiconducting behavior with an optical gap of 0.4 eV and electronic structure similar to that of the b axis at higher energies. The substantial temperature dependence of the vibrational modes in this direction reveals that the lattice of Li0.9Mo6O17 is not rigid. However, no noticeable change in the lattice through the 25 K metal-insulator transition is observed. Comparing x-ray and infrared data for several model materials, we establish an upper bound on the size of any lattice distortion in Li0.9Mo6O17. Based upon these combined results, we argue that localization effects dominate the bulk and microscopic properties of this material.