Figure 1: Structure and thermal conductivity of higher manganese silicides.
From: Twisting phonons in complex crystals with quasi-one-dimensional substructures
(a) Schematic illustrations of the crystal structure of Mn4Si7. The condition for a commensurate structure (MnnSi2n−m) satisfies the relationship ncMn=mcSi=c where n and m are integers and c, cMn and cSi are the lattice constants along the c axis for the HMS primitive cell, Mn sublattice and Si sublattice, respectively. (b) Temperature-dependent thermal conductivities of the HMS crystal measured in this work along the c and a axes. Shown for comparison are the reported thermal conductivity data of HMS (ref. 11), Bi2Te3 (ref. 18), PbTe (ref. 19) and Ba8Ga16Ge30 (ref. 20) crystals, and Si80Ge20 (ref. 21) and EuxCoSb3 (ref. 22) alloys. (c) Scanning electron microscopy (SEM) image of the HMS crystal synthesized in this work. The inset is the magnified SEM image showing the presence of MnSi layers with a thickness of about 600 nm in the HMS crystal. (d) High-resolution transmission electron microscopy (HRTEM) lattice fringe image of the HMS region of the crystal. (e) Selected area electron diffraction (SAED) of the HMS crystal along the 
zone axis indexed with respect to the Mn sublattice. (f) Neutron diffraction pattern of the HMS crystal indexed with respect to the Mn27Si47 phase. In both (e) and (f), the Si sublattice of a long cSi produces characteristic satellite reflections along the [001] direction of the HMS crystal.
