Thermoelectric properties of p-type Bi-Sb-Te compositionally graded thermoelectric materials with different barriers

In order to find more suitable materials as barriers and to improve the thermoelectric properties, p-type (Bi_(l-x)Sb_x)_2 Te_3 (x = 0.85, 0.9) two segments compositionally graded thermoelectric materials (CGTM) with different barriers were fabricated by conventional hot pressure method. Metals Fe, Co, Cu and Al were used as barriers between two segments. The effects of different barriers on thermoelectric properties of CGTM were investigated. The results show that metal Fe is more stable and suitable as the barrier.     

Thermoelectric properties of p—type Bi—Sb—Te Compositionally Graded thermodelectric materials with different barriers

In order to find more suitable materials as barriers and to improve the thermoelectric properties,p-type(Bi1-xSbx)2Te3(x=0.85,0.9) two segments compositionally graded thermoelectric materials(CGTM) with different barriers were fabricated by conventional hot pressure method.Metals Fe,Co,Cu and Al were used as barriers between two segments.The effects of different barriers on thermoelectric properties of CGTM were investigated.The results show that metal Fe is more stable and suitable as the barrier.     

Thermoelectric properties of p-type (Bi_(0.15)Sb_(0.85))_2Te_3-PbTe graded thermoelectric materials with different barriers

The p-type (Bi0.15Sb0.85)2Te3 and PbTe are typical thermoelectric materials used for low and middle temperature range and functional graded materials (FGM) is an inevitable way to widen the working temperature range. Here two segments graded thermoelectric materials (GTM) consisting of (Bi0.15Sb0.85)2Te3, PbTe and different barriers were fabricated by the common hot pressure method. Metals Fe, Mg and Ni were used as barriers between the two segments. The diffusion of different barriers between the barriers and bases were analyzed by electron microprobe analysis (EMA). The phase and crystal structures were determined by X-ray diffraction analysis (XRD). The thermoelectric properties were measured at 303 K along the direction parallel to the pressing direction. The results show that the compositional diffusion occurs when there is no barrier at the interface of the two segments, and the diffusion of Pb is most obvious; as the barrier material, the diffusion of metals Fe, Mg and Ni between different bases is not very obvious, and the thermoelectric properties of GTM is much better than that of the original segment.     

Thermoelectric properties of porous (Bi_(0.15)Sb_(0.85))_2Te_3 thermoelectric materials

In order to obtain thermoelectric materials with high figure of merit, the concept of Hollow (Vacuum) Quantum Structure or Effect and related thermoelectric materials design were proposed. To demonstrate the theory, the materials of (Bi0.15Sb0.85)2Te3 with porous structure have been fabricated. Their thermoelectric properties and the microstructure were investigated and compared with their density structure. It was found that the porous structure could improve their properties greatly.     

Effect of Y（Yttrium） Filling Fraction on Thermoelectric Properties of p-type Yy Fex Co4-x Sb12

Yttrium-filled sku, tterudites Yy Fex Co4-x Sb12 （ Y =0- 0. 40 ） were synthesized. The effect of Y filling fraction on thermoelectric properties of Yy Fex Co4-x Sb12 was investigated. All samples showed p-type conduct. The electrical conductivity decreased with increasing filling fraction y. The Seebeck coefficient inreased with increasing temperature. The lattice thermal conductivity decreased with increasing filling fraction y and showed the minimum value at a certain filling fraction y = 0.3. The effect of different filling atoms M（ M： Ba, Ce, Y） on the lattice thermal conductivity of MyFexCo4-xSb12 was discussed. The maximum ZT value of O. 7 was obtained for Y0.06 Fe0.7 Co3.3 Sb12 at 750 K.     

Solid State Reaction Synthesis and Thermoelectric Properties of Mg2Si doped with Sb and Te

Doped with Sb and Te, Mg₂ Si based compounds were prepared respectively by solid state reaction at 823K for 8h. Effects of dopants of Sb and Te on the structure and thermoelectric properties of the compounds were investigated. By calculating the values of the electrical conductivity for Sb-doped sample, the mechanism of electric conduction at 625 K is different. The figure of merit for sample doped with 0.4wt% Te at 500K is 2.4×10⁻³W/mK², and it reaches 3.3×10⁻³ W/mK² at 650K for the sample doped with 0.5wt% Sb. The values are more than 1.4 times and 2.3 times of the pure Mg₂Si sample. JIANG Hong-yi : Born in 1961     

Single-negative properties of Ba_2Co_（1.8）Cu_（0.2）Fe_（12）O_（22） and Ba_3Co_2Fe_（23.4）Zn_（0.6）O_（41） hexagonal ferrites

The electromagnetic properties of Ba2Co1.8Cu0.2Fe12O22 (Co2Y) and Ba3Co2Fe23.4Zn0.6O41 (Co2Z) were studied by measuring microwave scattering parameters.In the transmission spectra of Ba2Co1.8Cu0.2Fe12O22,a forbidden band emerges due to ferromagnetic resonance,and the permeability will turn to negative in the vicinity of the ferromagnetic resonance frequency.In the complex permittivity spectra of Ba3Co2Fe23.4Zn0.6O41,the negative permittivity can be obtained due to dielectric resonance.Therefore,Co2Y and Co2...