Structural and Electrical Properties Characterization of Sb1.52Bi0.48Te3.0 Melt-Spun Ribbons

Abstract

Melt-spinning (MS) has been reported as a promising tool to tailor the microstructure of bulk thermoelectric materials leading to enhanced thermoelectric performances. Here, we report on a detailed characterization of p-type Bi 0.48 Sb 1.52 Te 3 ribbons produced by melt-spinning. The microstructure of the melt-spun ribbons has been studied by means of X-ray diffraction, scanning and transmission electron microscopy (TEM). The analyses indicate that the ribbons are highly-textured with a very good chemical homogeneity. TEM reveals clear differences in the microstructure at large and short-range scales between the surface that was in contact with the copper wheel and the free surface. These analyses further evidence the absence of amorphous regions in the melt-spun ribbons and the precipitation of elemental Te at the grain boundaries. Low-temperature electrical resistivity and thermopower measurements (20-300 K) carried out on several randomly-selected ribbons confirm the excellent reproducibility of the MS process. However, the comparison of the transport properties of the ribbons with those of bulk polycrystalline samples of the same initial composition shows that MS leads to a more pronounced metallic character. This difference is likely tied to changes in deviations from stoichiometry due to the out-of-equilibrium conditions imposed by MS.

Structural and transport properties of quenched and melt-spun BixSb2−xTe3 solid solutions (x = 0.40 and 0.48)

“…PXRD patterns of the BixSb2-xTe3 samples: a) reference and melt-spun samples for x = 0.40, b) magnification of the region around the (015) peak. The PXRD patterns of the Ref andMS x = 0.48 samples are similar and can be found in our prior study[20].…”

“…detectable. This result can be attributed to the very high cooling rate undergone by the melt during the MS process that leads to homogeneous ribbons, as shown in our previous study [20].…”

“…These studies have evidenced that i) the best composition falls within the range 0.4 ≤ x ≤ 0.5, and ii) the thermoelectric performances achieved are significantly improved in MS samples compared to standard zoneleveling ingots. In a prior study on the melt-spun Bi0.48Sb1.52Te3 ribbons themselves, we showed that they are highly-textured and exhibit more pronounced metallic transport properties with respect to samples of similar chemical compositions prepared by conventional powder metallurgy, that is, quenched from the melt followed by fast sintering by spark plasma sintering [20]. A direct comparison between samples prepared by quenching in room-temperature water and by MS could provide additional information on the exact impact of the MS process on the transport properties, which are not directly accessible by a comparison to zone-levelingprepared polycrystals.…”

“…These studies followed pioneering works performed in the 1980s and 1990s on the binaries Bi2Te3, Sb2Te3 and Bi2Se3 prepared by MS [12][13][14][15][16]. Even if these remarkable values have been tempered recently with ZT values close to 1.1 -1.2 [17][18][19][20][21][22][23][24], all the studies showed that MS is a worthwhile mean for further optimizing the thermoelectric performances of Sb2Te3…”

A Review on Doped/Composite Bismuth Chalcogenide Compounds for Thermoelectric Device Applications: Various Synthesis Techniques and Challenges

“…Also, in nanostructured Bi 2 Te 3 /MnTe 2 , the ZT was found to be 0.26 at 480 K. 157 The sintered bulk materials of p-type Bi 0.52 Sb 1.48 Te 3 prepared using melt spinning and rapid sintering were found to depend on thermal conductivity of ambient gases with enhancement in ZT value of about 1.09 at 340 K. 158 To control the crystallographic preferred orientation, melt spinning method has been applied for CHI 3 -doped Bi 2 Te 2.4 Se 0.6 alloys with an optimized frequency of 300 rpm with ZT of 1.02 at 400 K. 119 The outstanding homogeneity and reproducibility by varying the stoichiometry have played a crucial role in the transport properties of p-type Bi x Sb 2−x Te 3 prepared by melt spinning. 159 The bulk materials of p-type Bi 0.52 Sb 1.48 Te 3 were synthesized by Yun et al, 160 and it was observed that an argon atmosphere could effectively inhibit heat loss and suppress the sublimation of tellurium. Therefore, the Bi 0.52 Sb 1.48 Te 3 sample showed the highest ZT of 1.09 at 340 K (Fig.…”