Search

Lead sulfide (PbS) is widely recognized as a promising n-type thermoelectric material for use in the middle-temperature range. Although it already exhibits favorable electronic and thermal properties, its thermoelectric performance could be further enhanced by addressing the disparity between the light and heavy bands in the conduction band, thereby optimizing electrical transport, and by modifying the strength of its chemical bonds to reduce lattice thermal conductivity. In this study, we demonstrate that introducing just small amounts of antimony (Sb) into PbS generates a unique combination of interstitial and substitutional doping that leads to a significant improvement in both directions. Substitutional doping enhances the degeneracy between the light and heavy bands, increasing carrier mobility. At the same time, interstitial doping introduces a new resonance state near the Fermi level, providing an additional channel for electron transport while boosting carrier concentration. These synergistic effects lead to a marked increase in the power factor of PbS, achieving an average power factor (PFavg) of 1.07 mW m−1 K−2 across the temperature range of 320–873 K. Moreover, Sb substitution for Pb induces a shift in the surrounding S atoms toward Sb, weakening their bonds with neighboring Pb atoms. This shift results in a coexistence of strong and weak chemical bonds, which effectively reduces lattice thermal conductivity. Additionally, the defect structures introduced by Sb doping effectively scatter phonons, further lowering lattice thermal conductivity. As a result, PbS doped with 0.5% Sb exhibits a figure of merit (ZT) of 0.73 at 873 K, which is approximately three times higher than that of undoped PbS. [ABSTRACT FROM AUTHOR]

Bi2Te3-based alloys are only commercial thermoelectric materials. While, currently, n-type Bi2Te 2. 7 Se 0. 3 -based alloys commonly have lower ZT values than those of p-type Bi 0. 5 Sb 1. 5 Te3 based alloys. In this paper, the influence of different amounts of dispersing honey on the thermoelectric performance of n-type Bi2Te 2. 7 Se 0. 3 alloys synthesized by the hydrothermal and hot-pressing methods was investigated. The carbon atoms contained in honey could increase lattice defects and grain boundary density effectively, and improved the Seebeck coefficient and suppress lattice thermal conductivity simultaneously. By adjusting the amount of honey, the maximum ZT value reached 0.82 at 423 K, which was approximately 65% higher than that of the pristine Bi2Te2.7Se0.3. [ABSTRACT FROM AUTHOR]

In this study, ceramic samples of Bi2Sr2Co2Oy + v wt% B2O3 (v = 0.0, 0.1, 0.2, 0.3, 0.4) were synthesized using the solid state reaction method, and the influence of B2O3 additive on their microstructure and thermoelectric properties were investigated. On one hand, the B2O3 additive acted as a sintering aid, enhancing carrier mobility. On the other hand, B2O3 dispersion served as a nano-second-phase, increasing hetero-interfaces and strengthen phonon scattering, thereby effectively suppressing lattice thermal conductivity. By dual optimization of both electric and thermal transport performance, the Bi2Sr2Co2Oy + 0.3 wt% B2O3 sample achieved a high ZT value (thermoelectric figure of merit) of 0.31 at 923 K, which was improved by approximately 33% compared with the pristine Bi2Sr2Co2Oy sample. [ABSTRACT FROM AUTHOR]

Bi2Te3-based alloys are currently the best room-temperature thermoelectric materials, and have been used widely in the field of thermoelectric refrigeration. Bi2Te3 ingots prepared by the zone-melting method provide convenience for large-scale commercial application. Currently, one trend is that the dimensionless thermoelectric figure-of-merit (ZT) value of the n-type Bi2Te2.7Se0.3 is slightly lower than that of the p-type Bi0.5Sb1.5Te3. In this paper, n-type Bi2Te2.7Se0.3 alloy ingots with large size were successfully prepared through the optimized zone-melting preparation process, and achieved a high ZT value of 1.16 at 360 K. This value is higher than all the n-type or p-type Bi2Te3-based ingots in current commercial applications. [ABSTRACT FROM AUTHOR]

Introducing the nanosecond phase into thermoelectric materials is an effective strategy to improve their thermoelectric properties. In this study, the influence of nano Y2O3 dispersion on the resistivity, Seebeck coefficient and thermal conductivity of Cu2Se + x mol% Y2O3 (x = 0, 0.5, 1.0, 2.0, 3.0) was investigated. Their resistivity and Seebeck coefficient have no obvious change under the combined effects of the microstructure and the energy filtering. Especially, Y2O3 dispersion can inhibit the recrystallization of Cu2Se and make the lamellar grains thinner, thus scattering phonon and reducing the thermal conductivity effectively. When x = 1.0, the thermal conductivity reaches a minimum of 0.65 W/K·m at 923 K. The dimensionless thermoelectric figure of merit (ZT) value of the Cu2Se + 1.0 mol% Y2O3 sample reaches 1.81 at 923 K. The study indicates that nano rare earth oxides are relatively effective second-phase that can reduce thermal conductivity, which may be further promoted for other thermoelectric materials. [ABSTRACT FROM AUTHOR]

Theoretically, nanosecond phase dispersion is an effective method to optimize the performance of thermoelectric materials due to the energy filtering effect and strong phonon scattering. Because of the chemical stability of La2O3, it may be used as a second phase material in Bi2Te2.7Se0.3 matrixes. After the introduction of La2O3, its electric transport performance decreases slightly, but its thermal transport performance increases further. Finally, its thermoelectric performance is optimized. At 455 K, the maximum dimensionless thermoelectric figure of merit (ZT) value of Bi2Te2.7Se0.3 + 0.5 wt% La2O3 reaches 0.97. The experimental results demonstrate that La2O3 dispersion can improve the thermoelectric properties of Bi2Te2.7Se0.3 effectively. [ABSTRACT FROM AUTHOR]

Bi2Te3 is a classical thermoelectrical material and has been applied widely in commerciality. In this paper, the influence of La2O3 dispersion as the nanosecond phase on the thermoelectric properties of Bi2Te3 was investigated. The Bi2Te3 nanopowders were prepared by the hydrothermal method. After adding the La2O3 nanopowders according to Bi2Te3 + s wt% La2O3 (s = 0 , 0.5, 1.0, 1.5), they were hot pressed into bulks in vacuum. The experimental results showed that the dispersed La2O3 as the nanosecond phase could enhance phonon scattering and suppress the thermal conductivity of Bi2Te3 effectively. Although their electrical resistivity increased due to the deteriorated carrier mobility, as a combined effect, the thermoelectric merit value (ZT) of the Bi2Te3 + 0.5 (or 1.0) wt% La2O3 was optimized and reached 0.61 at about 455 K. [ABSTRACT FROM AUTHOR]