Ionic conduction path, covalent bonding and phase transition of lithium-ion conductors

本文报道了La_<0.62>Li_<0.16>TiO_3钙钛矿结构的中子粉末衍射研究结果，确定了室温下锂离子的扩散路径。在77 K时，Li阳离子位于（002）La缺陷层的2c位，而在室温时，Li阳离子沿2c-4f-2c或2c-2d-2c连接线分布。我们已经证明，锂阳离子的概率密度在扩散路径上的2c和4f之间或2c和2d位置之间具有最小值，与之前的报告相比，瓶颈被认为位于2c，2d和4f位置。由于大部分Li离子不是位于4j A位，而是位于2c位，所以标题化合物的化学式不是（La_&lt;2/3-x&gt;，Li_<3x>，（Va_&lt;（A位）&gt;）_&lt;1/3-2x&gt;）_<A-site>TiO_3，而是（La_&lt;2/3-x&gt;，（Va_&lt;（A位）&gt;）_&lt;1/3+x&gt;）_<A-site>（Li_<3x>，（Va_&lt;（2c）&gt;）_&lt;1/4-3x&gt;）_<2c>TiO_3。本结论将有助于讨论 ...更多信息 利用中子衍射、高分辨同步辐射X射线粉末衍射和拉曼散射技术研究了40 nm、140 nm和430 nm钛酸钡（BaTiO 3）纳米粒子的晶体结构尺寸效应。用Rietveld方法，用中子粉末衍射数据，得到了26° ~ 778℃范围内Bi_2O_3晶格常数随温度的变化关系。设计并制作了一台适用于日本筑波光子工厂BL-4B_2实验站多探测器系统的新型电炉，用于测量1807 K高温下材料的高分辨同步辐射粉末衍射轮廓。利用同步辐射X射线粉末衍射数据研究了碘化铜（CuI）在300 K和760 K下的晶体结构。氮氧化钽（TaON）的研究中子和同步辐射衍射分析，以澄清负责这种材料的可见光活性的结构和电子特征。少

We have reported the results of a neutron powder diffraction study of La_<0.62>Li_<0.16>TiO_3 perovskite that determines the diffusion path of lithium cations at room temperature. At 77K, the Li cations are located at the 2c site on the (002) La deficient layer, while at room temperature, they spread over a wide area and migrate following the 2c-4f-2c or 2c-2d-2c tie line. We have demonstrated that the probability density of Li cations has a minimum between the 2c and 4f or between the 2c and 2d positions on the diffusion path, in contrast to the previous reports where the bottleneck has been thought to be located at the 2c, 2d and 4f positions. Since most of the Li cations are not located at the 4j A-site but at the 2c site, the chemical formula of the title compound is not (La_<2/3-x>, Li_<3x>, (Va_<(A-site)>)_<1/3-2x>)_<A-site>TiO_3, but (La_<2/3-x>,(Va_<(A-site)>)_<1/3+x>)_<A-site>(Li_<3x>,(Va_<(2c)>)_<1/4-3x>)_<2c>TiO_3. The present conclusion would be helpful when discussing the … More conduction mechanism of Li-ion conductors.A size effect on crystal structure has been investigated for barium titanate (BaTiO_3) nanoparticles of 40-, 140- and 430-run sizes, by means of neutron and high-resolution synchrotron X-ray powder diffraction and Raman scattering techniques. Temperature dependence of lattice parameters of bismuth sesquioxide (Bi_2O_3) has been obtained between 26°and 778℃ by the Rietveld method using neutron powder diffraction data. A new electric furnace has been designed and fabricated for measurements of the high-resolution synchrotron radiation powder diffraction profiles from materials at high temperatures up to 1807 K in air, suitable for the multiple-detector system installed at the BL-4B_2 experimental station of the Photon Factory in Tsukuba, Japan. Crystal structure of copper iodide (CuI) has been studied at 300 K and 760 K using synchrotron X-ray powder diffraction data. Tantalum oxynitride (TaON) is investigated by neutron and synchrotron diffraction analysis to clarify the structural and electronic features responsible for the visible-light activity of this material. Less