Solid State Synthesis of Ternary Thermoelectric Magnesium Alloy, Mg<SUB>2</SUB>Si<SUB>1&minus;<I>x</I></SUB>Sn<I><SUB>x</SUB></I>

Abstract

Profound understanding and survey of magnesium base intermetallic compounds is hindered by various difficulties in their processing and fabrication. Solid-state synthesis via the bulk mechanical alloying (BMA) is free from contaminations and segregation through high reactivity of elemental constituents against crucibles or vials. Magnesium-tin system is employed to demonstrate the solid-state reactivity to Mg 2 Sn from the elemental powder mixture. This process is characterized by the gradual solid-state reaction to Mg 2 Sn with processing time. Since the blended mixture of magnesium and tin with the initial molar ratio of Mg66.7%Sn33.3%, is repeatedly strained via BMA in the controlled conditions, the solid-state reaction advances monotonically with refinement of interparticle distance between magnesium and tin. Ternary semi-conductive compounds, Mg 2 Si 1Àx Sn x for 0 5 x 5 1, are also synthesized by this process. Thermoelectric properties of this ternary alloy are investigated to discuss the effect of tin content on the band-gap, the thermal conductivity, the Seebeck coefficient and the figure-of-merit. In addition, these data are compared to the previously reported results by using melt and solidified samples in order to describe the common features in the solidsolution type thermoelectric compounds. Furthermore, p-n transition behavior is also reported in this ternary alloy system.

Enhancing the zT Value of Bi-Doped Mg2Si0.6Sn0.4 Materials through Reduction of Bipolar Thermal Conductivity

“…As the band gap of Mg 2 Sn (0.36 eV) is smaller than that of Mg 2 Si (0.7 1 eV), the band gap of Mg 2 Si 1– x Sn x decreased with an increase in the value of x. , Thus, the band gap of Mg 2 Si 0.6 Sn 0.4 is larger than that of Mg 2 Si 0.4 Sn 0.6 , and therefore, the bipolar thermal conductivity of Mg 2 Si 0.6 Sn 0.4 is expected to be easier to suppress at higher temperatures.…”

Bridgman Growth of Mg2Sn1–xBix Single Crystals and Anisotropic Thermoelectric Properties

“…Thermoelectric materials can achieve direct conversion between thermal energy and electrical energy. 1,2 Among these materials, nontoxic and nonpolluting candidates such as Mg-based alloys have aroused the intensive interest of researchers. 3−6 According to classical thermoelectric theory, the material factor β ∼ (m*/m e ) 3/2 μκ L −1 can be used as the criterion for the selection of thermoelectric materials, where m* is the carrier effective mass, m e is the electron mass, μ is the mobility, and κ L is the lattice thermal conductivity.…”

Evaluation of Magnesium Tin Silicide Sintered Bodies Prepared by Liquid-Phase Pressure-Less Sintering

“…15,16) Special manufacturing methods are required because they are difficult to be sintered. 22) For example, spark plasma sintering (SPS), 410) hot press (HP), 1113) hot isostatic pressing, 21) and mechanical alloying 14) are utilized in general. SPS provides a high density with a short sintering time, but it restricts the size and shape of the sintering zig.…”