Thermoelectric performance of Mg2.2(Ge0.9Sn0.1) ternary solid solution doped with Ag, Bi, Ni and Sb

[Display omitted] •The effect of Bi, Sb and Ag doping on the appropriate X-rich (i.e., Si-, sn- or Ge-rich) member in Mg2X ternary series.•Effect of Ni doping on Mg2.2Ge0.9Sn0.1. solid solution.•Secondary phase formation in Mg2.2Ge0.9Sn0.1 solid solution.•RT lattice thermal conductivity of Mg2.2Ge0.9Sn0.1 ternary solid solution using Abeles model. Mg2.2(Ge0.9Sn0.1)0.94X0.06(X = Ag, Bi, Ni, Sb) ternary solid solutions were synthesized using a two-step solid state reaction followed by hot pressing. The effects elemental doping on thermoelectric properties of these compounds were studied in the temperature range of 300 to 800 K. The findings demonstrate that Bi, Sb, and Ni function as useful n-type dopants, with Bi being more efficiently in the solid solution of Mg2.2Ge0.9Sn0.1. Additionally, the findings indicate that Ag is less efficient in n-type doping. Finally, maximum ZT for the Bi-doped sample is 0.82 at 800 K because of its strong electrical conductivity and moderate Seebeck coefficient.