Synthesis of Lithium Silicides, Germanides and Stannides with Ion Exchange Materials

由于两个原因，元素Si、Ge和Sn的二元锂化合物是用于可再生能源的令人感兴趣的材料，即，e.它们可以用作阳极材料和半导体Si和Ge同素异形体的前体材料，具有令人感兴趣的光电性能。在初步的实验和理论研究中，申请人已经表明，九原子簇E9可以在溶液中氧化偶联，并且可以从含锂前体获得元素的新的亚稳同素异形体。理论研究也表明了含九原子团簇元素同素异形体的稳定性。具有直接带隙的材料显著提高太阳能电池的效率。在该项目中，将通过使用离子交换技术，从较重的、更容易获得的同系物开始，系统地开发具有9个原子簇E9的含锂Zintl相。在初步研究的过程中，通过在液氨中通过离子交换的这种化合物的新合成路线，由K4Sn9成功地合成了Li4Sn9，作为原理的证明。在下文中，应通过使用我们实验室开发的用于其他含锂化合物（例如，G. Li 7Ge 12）。在最好的情况下，这将导致仍然包含9个原子簇并具有直接带隙的元素的新修改。

For two reasons binary lithium compounds of the elements Si, Ge and Sn are interesting materials for renewable energy sources, i. e. they can serve as anode materials and as precursor materials for semiconducting Si and Ge allotropes with interesting optoelectronical properties. In preliminary experimental and theoretical studies the applicant has shown that nine-atom clusters E9 can be oxidatively coupled in solution, and that new metastable allotropes of the elements can be obtained from lithium-containing precursors. The stability of allotropes of the elements which contain nine-atom clusters has also been indicated by theoretical investigations. Materials with direct band gaps significantly increase the efficiency of solar cells. Within this project the class of lithium-containing Zintl phases with nine-atom clusters E9, which are not directly accessible so far, are to be developed systematically, starting from the heavier, better-accessible homologues by using ion exchange techniques. The successful synthesis of Li4Sn9 from K4Sn9 via this novel synthetic route for this kind of compounds by ion exchange in liquid ammonia in the course of preliminary studies serves as a proof of principle. In the following, the lithium in the resulting products should be removed oxidatively by using established methods developed in our laboratory for the delithiation of other lithium-containing compounds (e. g. Li7Ge12). This should in best-case lead to new modifications of the elements which still contain the nine atom clusters and possess direct band gaps.