Composition-dependent Thermoelectric Properties Research Articles

Thermoelectric properties of BiCuSO doped with Pb

BiCuSeO based oxide show excellent thermoelectric performance due to its low thermal conductivity and moderate Power factor. There is rare study on the same crystal structured BiCuSO with lower cost and more earth abundance. The thermoelectric performance of BiCuSO is limited by its high resistivity result from its low carrier concentration and large band gap. In this paper, p-type polycrystalline BiCuSO doped with Pb was fast prepared by one-step high pressure method and the composition dependent thermoelectric properties was studied. The electrical resistivity and Seebeck coefficient of Bi1-xPbxCuSO both decreased monotonically with increasing Pb content due to the increased carrier concentration. The power factor was improved and the thermal conductivity was suppressed by Pb doping. The maximum figure of merit, ZT∼0.14 @ 700 K was obtained for the Bi0.975Pb0.025CuSO sample, which makes them promising candidates for thermoelectric applications.

First-principles studies of the TE properties of [110]-Ge/Si core/shell nanowires with different surface structures

Based on first-principle electronic structure calculations and Boltzmann transport theory, we investigate the composition-dependent thermoelectric properties of germanium/silicon core/shell [110]-oriented nanowires, as well as the surface passivation effects. The results demonstrate that the ZT values depend on the surface structure and the Ge/Si ratio. Significantly, for n-type [110]-Ge/Si core/shell NWs (about 2.6 nm in diameter) ZT = 0.65 at 300 K can be obtained, that is 65 times that of bulk Si, and 1.8 times that of SiNW without the core/shell structure at the same temperature.

Thermoelectric properties of PbTe1−xSex alloys prepared by high pressure

N-type thermoelectric alloys PbTe1−xSex were prepared by high pressure technique and the composition-dependent thermoelectric properties were studied at room temperature. The measurement results indicate that the electrical properties could be tuned effectively through chemical partial substitution of Se with Te. Thermal conductivity of PbTe was depressed largely by alloying with PbSe. The maximum figure of merit, Z=1.04×10−1K−1, was obtained for the sample of PbTe0.75Se0.25, which is about two times higher than that of unalloyed PbTe. These results indicate that alloying with PbSe under high pressure provides a viable and controllable way of tuning the thermoelectric properties for PbTe.

Theoretical study on thermoelectric properties of Mg2Si and comparison to experiments

Mg2Si has been regarded as a potential candidate for thermoelectric applications in middle-temperature range (500–900K). In order to better understand the temperature, doping level and composition dependent thermoelectric properties, we performed simulations that are based on the semi-classical electronic transport theory and the empirical lattice thermal conductivity model. The temperature and doping level dependence of the calculated Seebeck coefficients and electrical conductivity agree qualitatively with the previous experiments. By considering the influence of the chemical composition on the lattice thermal conductivity, we further estimated the thermoelectric figure-of-merit (ZT) for the Sb-doped Mg2Si samples. The results reproduced the temperature variation trends of the ZT values in the literature. The current work represents an attempt to combine the first-principles tools and the empirical models to evaluate the TE properties of the Mg2Si materials. It may shed some light on developing Mg2Si-based thermoelectric devices in the future.

Invited paper: Composition-dependent electrical properties of ternary AgxSb1−xTey thin films synthesized by cationic exchange reaction

Ternary silver antimony telluride (AgxSb1−xTey) thin films with tailored compositions were synthesized by a cationic exchange reaction of thermally evaporated antimony telluride thin films, as a simple and costeffective approach. The composition of AgxSb1−xTey thin films was controlled by the reaction time. Temperaturedependent electrical properties of the AgxSb1−xTey thin films demonstrated phase transition behavior from 323 K to 343 K. The composition-dependent thermoelectric properties (i.e., electrical resistivity (ρ), Seebeck coefficient (S) and power factor (S2ρ)) of the as-deposited Sb54Te46, the transformed AgxSb1−xTey and the annealed AgxSb1−xTey thin films were investigated as a function of temperature.

Thermoelectric properties of p-type pseudo-binary (Ag 0.365Sb 0.558Te) x–(Bi 0.5Sb 1.5Te 3) 1−x ( x=0–1.0) alloys prepared by spark plasma sintering

In this paper, pseudo-binary (Ag 0.365Sb 0.558Te) x –(Bi 0.5Sb 1.5Te 3) 1− x ( x=0–1.0) alloys were prepared using spark plasma sintering technique, and the composition-dependent thermoelectric properties were evaluated. Electrical conductivities range from 7.9×10 4 to 15.6×10 4 Ω −1 m −1 at temperatures of 507 and 318 K, respectively, being about 3.0 and 8.5 times those of Bi 0.5Sb 1.5Te 3 alloy at the corresponding temperatures. The optimal dimensionless figure of merit ( ZT) of the sample with molar fraction x=0.025 reaches 1.1 at 478 K, whereas that of the ternary Bi 0.5Sb 1.5Te 3 alloy is 0.58 near room temperature. The results also reveal that a direct introduction of Ag 0.365Sb 0.558Te in the Bi–Sb–Te system is much more effective to the property improvement than naturally precipitated Ag 0.365Sb 0.558Te in the Ag-doped Ag–Bi–Sb–Te system.

Electrical transport and high thermoelectric properties of PbTe doped with Bi 2Te 3 prepared by HPHT

In this paper, n-type lead telluride (PbTe) compounds doped with Bi 2Te 3 have been successfully prepared by high pressure and high temperature (HPHT) technique. The composition-dependent thermoelectric properties of PbTe doped with Bi 2Te 3 have been studied at room temperature. The figure-of-merit, Z, for PbTe is very sentivite to the dopants, which could be improved largely although the doped content of Bi 2Te 3 is very small (<0.08 mol%). In addition, the maximum value reaches to 9.3×10 −4 K −1, which is about 20% higher than that of PbTe alloyed with Bi 2Te 3 sintered at ambient pressure (7.6×10 −4 K −1) and several times higher than that of small grain size PbTe containing other dopants. The improved thermoelectric performance in this study may be due to the effect of high pressure and the low lattice thermal conductivity resulting from Bi 2Te 3 as source of dopants.

Electrical transport and thermoelectric properties of PbTe doped with Sb 2Te 3 prepared by high-pressure and high-temperature

In this paper, PbTe samples doped with Sb 2Te 3 have been successfully prepared by the high-pressure and high-temperature (HPHT) technique and the composition-dependent thermoelectric properties of PbTe have been studied at room temperature. Sb 2Te 3 exhibit the same character as the other dopants used for optimizing the carrier concentration of PbTe while the carrier concentration of PbTe prepared at ambient pressure is not sensitive to the Sb 2Te 3 content. The lattice thermal conductivity, which is lower than that of prepared by hot-pressing, decreases with increase of Sb 2Te 3. The figure-of-merit, Z, increases first and then decreases slowly with an increase of Sb 2Te 3 content and a maximum value of 8.7 × 10 −4/K was obtained with 0.05 mol% Sb 2Te 3 doped. This value is much higher than that PbTe doped with PbI 2 prepared at normal pressure with the same carrier concentration. These results indicate that HPHT technique may be helpful to prepare thermoelectric materials with enhanced thermoelectric properties.

Composition-dependent thermoelectric properties of PbTe doped with Bi 2Te 3

The composition-dependent thermoelectric properties of PbTe doped with Bi 2Te 3 have been studied at room-temperature. The electrical resistivity and the Seebeck coefficient in absolute value decrease with an increase of Bi 2Te 3. A sharp maximum in the Seebeck coefficient at 0.3 mol% Bi 2Te 3 indicates that an electronic topological transition is occurred in PbTe alloyed with Bi 2Te 3. The total thermal conductivity nearly keeps constant and the parts of lattice, which are much lower than those doped with PbI 2 prepared by hot-pressing, linearly decrease with increasing Bi 2Te 3. The figure of merit shows a maximum value of 7.63 × 10 −4 K −1, which is several times higher than that of PbTe containing other dopants. The high thermoelectric performance is explained by electronic topological transition induced by alloying.

High Thermoelectric Properties of PbTe Doped withBi2Te3 and Sb2Te3

The composition-dependent thermoelectric properties of lead telluride(PbTe) doped with bismuth telluride (Bi2Te3), antimonytelluride (Sb2Te3) and (BiSb)2Te3 have beenstudied at room temperature. All the samples exhibit small thermalconductivity. The figures of merit, 7.63, 1.03 and 8.97×10−4,have been obtained in PbTe with these dopants, respectively. Thesevalues are several times higher than those of PbTe containing otherdopants with small grain sizes. The high thermoelectric performance isexplained by electronic topological transition induced by alloying. Theresults indicate that these dopants are effective to enhance thethermoelectric performance of PbTe.

Composition-Dependent Thermoelectric Properties of PbTe Doped with Sb&lt;SUB&gt;2&lt;/SUB&gt;Te&lt;SUB&gt;3&lt;/SUB&gt;

Although there are many reports on PbTe-SnTe and Bi 2 Te 3 -Sb 2 Te 3 systems with improved thermoelectric performance due to reduced lattice thermal conductivity, only few experimental data exist on PbTe-Sb 2 Te 3 system. Inthis report, the composition-dependent thermoelectric properties of PbTe doped with Sb 2 Te 3 have been studied at room-temperature. It is worth noting that the lattice thermal conductivity is only about 1 W/K.m as the contents of Sb 2 Te 3 is larger than 0.8 mol%. In addition, the figure of merit shows a maximum value of 1.03 x 10 - 3 K - 1 with the content of Sb 2 Te 3 at 0.8 mol% which is the highest value obtained in doped bulk PbTe samples and is several times higher than that of PbTe containing other dopants with small grain sizes. This confirms that Sb 2 Te 3 is one of the best dopants for PbTe to enhance its thermoelectric performance.