Y.G. Xiao

In Situ Precipitation of Te Nanoparticles in p-Type BiSbTe and the Effect on Thermoelectric Performance

Through zone melting method, a certain amount of Te nano precipitations were in situ generated in the p-type BiSbTe matrix because of the addition of graphene. Both the microstructure and thermoelectric performance were investigated. Increased carrier concentration was obtained to improve the electrical performance, and the lattice thermal conductivity was simultaneously lowered about 25% by Te nano precipitations as phonon scattering centers. Consequently, an optimization of the thermoelectric figure-of-merit ZT between 375 and 550 K was achieved.

Enhanced thermoelectric figure of merit in p-type Bi0.48Sb1.52Te3 alloy with WSe2 addition

P-type Bi0.48Sb1.52Te3 alloys added with WSe2 were achieved via the zone melting method. The electrical performance was improved due to the increased carrier concentration, while the lattice thermal conductivity was simultaneously decreased, mainly due to the numerous types of nanoprecipitates produced, such as the second phase, antisite substitution and interfaces with different scales. As a result, a 23% improvement in the thermoelectric figure of merit zT was obtained with the addition of WSe2, making these composites more attractive for commercial applications.

Enhanced thermoelectric figure of merit in p-type BiSbTeSe alloy with ZnSb addition

We have prepared p-type BiSbTeSe alloys with different ratios of ZnSb addition by a zone melting method. The microstructure characterization shows that a second phase of ZnSeTe was generated in the matrix. Due to the ZnSb addition, the carrier concentration was increased, thus improving the electrical performance (power factor, α2σ), while the lattice thermal conductivity (κL) was simultaneously decreased, mainly due to the introduced defects, such as anti-site substitution, the second phase and interfaces with different scales. As a result, a significant improvement in the thermoelectric figure of merit ZT was obtained, especially above 370 K, which is very beneficial for commercial applications in power generation.

Thermoelectric performance of the ordered In4Se3–In composite constructed by monotectic solidification

In4Se3 has recently been found to be a layered compound which shows promising thermoelectric (TE) properties. In the present study, a textured In4Se3-based material grown by the zone melting technique is found to be a composite with elemental indium embedded in the In4Se3 matrix. The TE properties of this composite are evaluated and a maximum figure of merit ZT of 0.9 is achieved in the direction perpendicular to the growth direction. Such a result should provide a useful guidance for composition control towards further ZT enhancement in this material.

Effect of dehydrated-attapulgite nanoinclusions on the thermoelectric properties of BiSbTe alloys

Dehydrated-attapulgite (D-ATP) is a kind of oxide possessing nanorod structure; its major component is SiO2 with Mg2+ and Al3+ cations. Here, we fabricated p-type BiSbTe alloys with D-ATP nanoinclusions by zone melting method and investigated their thermoelectric performance. Both the electrical and thermal transport properties have been optimized by adding D-ATP, especially the lattice thermal conductivity was decreased significantly. The maximum thermoelectric figure of merit ZT reached 1.3 at 420 K, which is a very profitable value for commercial applications.

Crystal structure and spin reorientation transition of Tb1−xYxFe11Mo compounds

The structural and magnetic properties of mixed compounds Tb1-xYxFe11Mo with x = 0-1.0 have been investigated by means of x-ray diffraction and magnetic measurements. The compounds crystallize in the tetragonal ThMn12-type structure with space group I4/mmm. The lattice parameters a, c and the unit-cell volume V vary slightly with the Y content, since the atomic radius of Y is close to that of Th. The Curie temperature of the compounds increases for x <= 0. 1, then decreases with the increase in the Y concentration. Spin reorientation phenomena in the Tb1-xYxFe11Mo compounds have been studied in detail. The room temperature easy-magnetization direction of Tb1-xYxFe11Mo compounds changes from planar to the c-axial with increasing Y concentration. Variation of the anisotropy constants of the Fe-sublattice K-1(Fe) (T) with temperature is determined experimentally. By minimizing the magnetocrystalline anisotropy energy, the derived spin reorientation temperature for the Tb1-xYxFe11Mo system shows reasonable agreement with the observations.