Thermoelectric Properties of Nanocrystalline PbTe Synthesized by Mechanical Alloying

Abstract

In this work, nanocrystalline lead telluride powder was synthesized from high-purity elements by mechanical alloying by means of a planetary ballmilling procedure. The milling medium was tungsten carbide, and the diameter of the balls was varied in order to investigate the effect on the structural features of the material. Phase transformations and crystallite evolution during ball-milling were followed by powder x-ray diffraction (PXRD). The broadened PXRD peaks were analyzed with Voigt functions, revealing small crystalline size and stress introduced during the mechanical alloying process. Transmission electron microscopy (TEM) studies confirmed the material's nanostructure, as well as the effect of ball diameter on the size of the crystals. Thermoelectric properties are discussed in terms of the Seebeck coefficient and the nominal carrier concentration, as determined by Hall-effect measurements. The enhancement of the Seebeck coefficient is reported to be higher compared with other PbTe-based nanocomposites.

Synthesis and Ball Milling Effect on Thermal Conductivity of PbTe Based Alloys

“…Maximum fragmentation in our material was obtained after about 5–7 h grinding for PbTe:Cr,I and after ∼10–15 h for PbTe:Ag,La, which is slightly lower comparing with literature . As can be seen, longer milling times resulted only in small changes in the crystallite diameters.…”

“…Three different grinding times (5, 15 and 25 hours) examined in this work were selected on the basis of literature . Generally, milling time decreases with increasing energy of the used mill.…”

“…For instance, J. Martin, J.P. Heremans and Ch. Papageorgiou with coworkers studied PbTe structures with ∼300–400 nm, ∼30–60 nm and ∼5–50 nm particles, respectively. The size‐dependent Seebeck coefficient measurements show enhancement in S with decreasing particle size in each case.…”

Mechanochemical synthesis and thermoelectric properties of high quality magnesium silicide

“…16 This method has been successfully used for the synthesis of several thermoelectric materials including Bi 2 Te 3 , 17,18 CoSb 3 , 19 Si 1Àx Ge x , 20-24 La 3 Te 4 , 10 and PbTe. 25,26 The ball milling technique is ideal for brittle materials due to the constant fracturing and welding during milling. 15 However, because of the ''softness'' and ductility of Mg and its high reactivity with oxygen, magnesium silicide has been a difficult material to synthesize via ball milling.…”

Thermoelectric Performance of Mechanically Mixed BixSb2-xTe3—ABS Composites

“…High purity Bi x Sb 2-x Te 3 (BST) powders were produced by two different methods: melting and mechanical alloying [ 17 , 18 , 19 ]. The p-type BST x = 0.3 powder was fabricated by melting, while BST (x = 0.2, 0.4, 0.5) solid solutions were prepared by the mechanical alloying method.…”