Synthesis of p-type Mg2Si1-xSnx with x = 0-1 and optimization of the synthesis parameters

Abstract

Mg 2 Si is a promising thermoelectric material in the mid-temperature region 500 -800 K.Development of Mg 2 Si based thermoelectric generators requires both good n-and p-type materials. While the thermoelectric properties n-type Mg 2 (Si,Sn) materials are good, those of the corresponding p-type are not as much. Therefore, optimizing p-type solid solution of magnesium silicide and magnesium stannide is highly desired. We employ high energy ball milling for efficient synthesis of p-type Mg 2 (Si,Sn) and investigate the effect of milling time, sintering temperature, and holding time on the thermoelectric properties of p-type Mg 2 Si 1-x Sn x with x = 0-1. We can show the synthesis of p-type Mg 2 (Si,Sn) for the whole compositions using Li as a dopant. We have also studied the effect of the synthesis parameters (milling time, sintering temperature, and holding time) on the phase purity, functional homogeneity and thermoelectric properties. The phase purity increases with longer milling time. The functional homogeneity decreases with higher sintering temperature and longer holding time.The optimum synthesis condition for x = 0.6 leads to ~ 0.6 at 700 K, which is one of the highest value reported for p-type Mg 2 (Si,Sn).

Systematic analysis of the interplay between synthesis route, microstructure, and thermoelectric performance in p-type Mg2Si0.2Sn0.8

“…P-type Mg 2 Si 0.2 Sn 0.8 samples were synthesized using two different synthesis methods: high energy ball milling and induction melting, both followed by current assisted sintering. The detailed procedure of the BM synthesis is described in a previous report [42]. [47,48].…”

“…Using the well-established single parabolic band (SPB) model, we have systematically investigated the differences of Li-doped Mg 2 Si 0.2 Sn 0.8 fabricated by two popular synthesis routes: high energy ball milling (BM) and induction melting (IM) [14,18,42]. The composition was chosen because Li is the most efficient dopant for p-type Mg 2 Si 1-x Sn x and the samples with x = 0.8 have similar efficiency as the samples with x = 0.6 but a higher power factor [32,43]; they are also further outside the reported miscibility gap which is important for long term stability [44][45][46].…”

Developing Contacting Solutions for Mg2Si1–xSnx-Based Thermoelectric Generators: Cu and Ni45Cu55 as Potential Contacting Electrodes

“…These pressing conditions have been selected as to obtain optimal TE properties for both compositions [34][35] . All studied samples had a high relative density (≥ 97%).…”

“…All studied samples had a high relative density (≥ 97%). Further details on measurements of Seebeck coefficient and electrical conductivity can be found in the literature [34][35][36] . As joining temperatures are preferred to be as low as possible, 500 °C was also tried for both electrodes, but it was not sufficient for a good adhesion to the thermoelectric material.…”

Experimental investigation of the predicted band structure modification of Mg2X (X: Si, Sn) thermoelectric materials due to scandium addition

“…The elements were weighed according to the desired compositions with stoichiometries A systematic study of optimal sintering temperature vs Si:Sn content can be found in Ref. 23. The powder samples were sintered by a direct-current sintering press (DSP 510 SE) from Dr. Fritsch GmbH.…”