High thermoelectric performance in Sn-substituted α-As₂Te₃

Abstract

Substitution of Sn for As in α-As2Te3 enhances the thermoelectric performances with a maximum ZT of 0.8 at 523 K.

High-temperature thermoelectric properties of the β-As2−xBixTe3 solid solution

“…12 Remarkably, the ZT values achieved at 300 K were similar to those measured in Sn-substituted samples, suggesting that interesting thermoelectric performances could be obtained at higher temperatures. 12 Herein, we extend these investigations with a detailed study of the thermoelectric properties at moderately high temperatures (300-423 K) of polycrystalline β-As 2−x Bi x Te 3 samples in the homogeneity range. The substitution of Bi for As results in a significant increase in the ZT values with respect to the unsubstituted phase β-As 2 Te 3 with a peak ZT of 0.7 at 423 K for x = 0.017 perpendicular to the pressing direction.…”

“…However, due to the narrow compositional range that can be reached in the β-As 2−x Bi x Te 3 solid solution, Bi does not push the peak ZT closer to room temperature. As noted in our prior study, 12 the anisotropy in the electrical resistivity and in the thermal conductivity of β-As 2−x Bi x Te 3 does not compensate each other, giving rise to different ZT values in the parallel and perpendicular directions. Although the hole concentration only slightly changes with the Bi content, the ZT increases thanks to enhanced power factors achieved at 423 K upon Bi alloying.…”

“…9 Interestingly, both α-As 2 Te 3 and β-As 2 Te 3 phases are semiconductors that meet the aforementioned requirements. [10][11][12][13][14] In particular, they share the remarkable feature of being poor thermal conductors with lattice thermal conductivities well below 1 W m −1 K −1 above 300 K. Maximum ZT values of 0.8 at 523 K and 0.65 at 423 K were achieved in α-As 2 Te 3 and β-As 2 Te 3 , respectively, using the substitution of Sn for As as a tuning parameter of the hole concentration. 10,13 a Author to whom correspondence should be addressed.…”

“…2,10,[22][23][24][25][26][27] In the parallel direction, κ L approaches the lowest limit of the thermal conductivity (Figure 2(c)) estimated using the model developed by Cahill and Pohl and the measured longitudinal and transverse sound velocities. 13,[28][29][30] Figure 2(d), which shows the variations in temperature of the ZT values, indicates that ZT increases with temperature for all samples. The peak ZT of 0.7 at 423 K achieved in the x = 0.017 sample in the perpendicular direction represents an increase of 40% compared to the parent compound and evidences the beneficial influence of Bi on the thermoelectric properties of β-As 2 Te 3 .…”

“…SEM images collected in backscattering electron mode confirmed the phase-pure nature of the samples for x ≤ 0.035. 12 Hence, only the chemical compositions and transport properties of single-phase samples (x ≤ 0.035) were subsequently studied. EPMA measurements confirmed the very good chemical homogeneity of the matrix and revealed an excellent correlation between the nominal and actual compositions (see Table I).…”