Structural and thermoelectric properties ofAgSbTe2-AgSbSe2pseudobinary system

Abstract

Structural properties of the AgSbTe 2 -AgSbSe 2 pseudobinary system were examined using thermal analysis, scanning electron microscopy, and x-ray powder diffractometry. It was found that partial substitution of Te by Se atoms leads to stabilization of the cubic crystal structure of alloys. The electronic-transport properties of materials were measured in order to investigate carrier conduction, band-gap features, and thermoelectric properties. The undoped homogeneous solid solution exhibits extremely low thermal conductivity of 0.5 W m −1 K −1 , a very large positive Seebeck coefficient of about 400-600 V K −1 at room temperature, low carrier densities of 10 16 -10 18 cm −3 , and thermally activated conduction. The influence of alloying on thermal-conductivity mechanisms and electron properties was discussed. The highest experimental dimensionless figure of merit ZT of the undoped AgSbSe 0.25 Te 1.75 sample is about 0.65 at a temperature of 520 K. The influence of doping on enhancement of thermoelectric properties of these materials was analyzed and optimal values of transport parameters were estimated.

Analysis of the Influence of Thermal Treatment on the Stability of Ag1−xSb1+xTe2+x and Se-Doped AgSbTe2

“…The form of the curves relates to hysteresis presented in prior figures. Results are comparable with some of the reported data 2,12 and slightly lower than those determined by Du et al 3 Discrepancies might be induced mostly by instability of b phase. Despite relatively slow kinetics of the process of decomposition, illustrated by x-ray analysis (Fig.…”

“…There is a strong conviction in the literature that it is possible to obtain metastable homogeneous AgSbTe 2 only as a result of fast cooling down and quenching of liquid alloy with the same chemical composition. [2][3][4]9,11,12,14 However, we have found that XRD patterns of both slowly cooled and quenched samples do not differ substantially (Fig. 3) (Figs.…”

“…Wu et al 11 seem to settle this discrepancy. According to them, annealing at T = 523 K leads to the decomposition of b phase, which is not observed after thermal treatment in 673 K. 11 Moreover, differential scanning calorimetry (DSC) analyses performed by Wojciechowski et al also confirm decomposition in 633 K. 12 However, there are still some discrepancies considering the existence of a and e solid solutions and the range of existence of b phase.…”

“…2,13 In this study, we have tried to systematize the knowledge on AgSbTe 2 -based materials, revise both phase diagrams 9,10 and results of structural and thermoelectric measurements presented in the literature. [2][3][4]12,14 …”

Surface oxidation and thermoelectric properties of indium-doped tin telluride nanowires

“…[66][67][68][69][70] As shown in Figure 7c, the κ at 300 K is 2. 76 The lattice thermal conductivity κ L is then determined by subtracting the total thermal conductivity by the electronic thermal conductivity. Both κ e and κ L are plotted in Figure 7c, κ e increases as the temperature is raised, while κ L shows a non-monotonic behavior with a maximum value at 60K.…”