Structural Investigation and Indium Substitution
in the Thermoelectric Mn2.7Cr0.3Si4Al2−xInx Series
Following the recent discovery of the promising Mn2.7Cr0.3Si4Al2 thermoelectric compound (having, e.g., automotive, industrial, and solar conversion applications), structural characterization by x-ray single-crystal diffraction analysis has been performed. This layered material is composed of two distinct crystallographic sites where both (Mn, Cr) and (Al, Si) are randomly distributed. The deduced crystallographic parameters were then confirmed by powder x-ray diffraction analysis through a temperature dependence of the phase stability, showing at the same time chemical stability up to 873 K. Taking into account the two distinct crystallographic sites highlighted, samples possessing two guest elements, one on each site, were then synthesized to improve the thermoelectric properties. A solid solution is found in the system Mn2.7Cr0.3Si4Al2−xInx with x varying from 0 to 0.2. Thus, double-substituted samples were studied by x-ray diffraction, electrical, and thermal measurements. The present paper describes and discusses the experimental results obtained.