Enhanced thermal rectification in graded Si Ge1- alloys

We evaluate the rectification coefficient of the heat flux in graded SicGe1-c alloys, both for longitudinal heat flow along a direction z and radial heat flow along a direction r, and for linear stoichiometric spatial distributions c(z) and c(r), with c is an element of[0,1]. To this end, we take an expression for the thermal conductivity lambda(c, T) fitting the experimental data in the whole interval 0 <= c <= 1, for different values of the temperature T. Such an expression leads to a highly nonlinear evolution equation for the temperature. It turns out that the systems under consideration are very efficient as thermal rectifier in the full stoichiometric range, and can be used as thermal diode. (C) 2020 Elsevier Ltd. All rights reserved.