Improvement of thermoelectric properties of chimney-ladder compounds by controlling compositional/structural grade

用x射线粉末衍射、扫描电镜和透射电镜研究了锰取代三硅化钌合金的相关系。在<1-x>Ru_2Si_3和Mn_4Si_7之间的较宽的成分范围内，形成了一系列的烟囱状梯状相Ru_ Mn_xSi_y。在Ru-Mn-Si系统中定向凝固的烟囱状梯状化合物表现出包含不同烟囱状梯状相的柱状畴的显微结构，相邻相之间具有成分界面。尽管组成的变化，过渡金属（Ru/Mn）亚晶格是连续的界面上，而Si亚晶格是不连续的。定向凝固合金沿着横向的晶格热导率通过增加成分界面的密度而降低，同时保持电性能。

Phase relationships of manganese-substituted ruthenium sesquisilicide alloys have been investigated by using x-ray powder diffraction, scanning and transmission electron microscopy. A series of chimney-ladder phases Ru_<1-x>Mn_xSi_y are formed over a wide compositional range between Ru_2Si_3 and Mn_4Si_7. Directionally solidified chimney-ladder compounds in the Ru-Mn-Si system exhibit a microstructure containing columnar domains of different chimney-ladder phases with compositional interfaces between adjacent phases. Despite a compositional variation, the transition-metal (Ru/Mn) sublattice is continuous over the interface while the Si sublattice is discontinuous. The lattice thermal conductivity of the directionally solidified alloys along the transverse direction decreases by increasing the density of the compositional interfaces while the electrical properties are preserved.