Heat flux rectification in graded SicGe1−c: Longitudinal and radial heat flows

Abstract We evaluate the rectification coefficient of the heat flux in graded Si c Ge 1 − c for longitudinal and radial heat flows, and for different stoichiometric spatial distributions c ( z ), either in the full stoichiometric range c ∈ [ 0 , 1 ] , and in the ranges with steepest variation of heat conductivity with composition, namely c ∈ [ 0 , 0.1 ] and c ∈ [ 0.9 , 1 ] . It turns out that rectification is more efficient in the mentioned ranges than in the full stoichiometric range. In the cylindrical case, the inhomogeneity in the length of internal and external perimeters of the system (geometrical inhomogeneity) is combined with the material inhomogeneity of the concentration profile, in contrast to the rectilinear situation, and influences the rectification coefficient, enhancing or reducing it, depending on the situation.