Maxwell–Garnett model for thermoelectric materials

•We found the thermoelectric field distribution of spheroid inside a matrix material•The Maxwell–Garnett approach was adopted for granular thermoelectric materials•The model was illustrated for MgAg0.97Sb0.99 inclusions placed in a matrix of Bi2Te3•Impact of the spheroid geometry on effective properties of a composite is analyzed The paper studies the problem of an extended thermoelectric spheroid placed in a thermoelectric matrix. The external electric field is assumed to be uniform. Despite the nonlinear nature of the equations, the solution of the problem can be found as a sum of Legendre functions and polynomials. The solution obtained is used to find the effective values of electrical and thermal conductivities, as well as the thermopower for a composite medium consisting of a set of randomly located spheroids. As an example of the model application, we consider a composite consisting of spheroidal inclusions MgAg0.97Sb0.99 placed in a matrix of Bi2Te3.