Search

The successful application of nanotechnologies in enhancing thermoelectric properties of n-type Bi2Te3 alloys remains a formidable challenge, despite significant advancements in their p-type counterparts. The distinctive challenges inherent to n-type materials include the complex relationships between defect structures and electron concentration, and the strong anisotropy of thermoelectric properties. Electrons originate from various defect structures, such as impurity dopants, vacancies, antisite defects, and grain/domain boundaries, which sensitively varies depending on material synthesis processes. Moreover, the pronounced anisotropic nature of thermoelectric properties requires grain alignment along specific crystallographic directions. Therefore, the challenges in achieving high-performance n-type Bi2Te3 alloys lie in the difficulties of independently controlling defect structures (electron concentration), textured microstructures (electron/phonon transport property), and nanofeatures. This review aims to provide a comprehensive understanding of the difficulties and challenges associated with these aspects, and to discuss potential routes for realizing high-performance n-type Bi2Te3 alloys. [ABSTRACT FROM AUTHOR]

In the present work, Cu and Ni nanofluids were synthesized using the pulsed wire evaporation (PWE) method in the different aqueous medias, namely (ethanol and ethylene glycol), and the effects of the aqueous media on the dispersion state, stability, and particle size of nanoparticles were studied. The size and morphology of synthesized nano-particles were investigated by transmission electron microscopy (TEM). Also, the dispersion stability of the nanofluids was evaluated by turbiscan analysis. The TEM results showed that the nano-particles were spherical in shape, and the average particle size was below 100 nm. The average particle size of the Cu nano-particles was smaller than that of Ni, which was attributed to a difference in the specific sublimation energy of the elements. Moreover, ethylene glycol (EG) exhibited higher suspension stability than ethanol. Finally, the dispersion stability of Cu@EG displayed the highest value due to lower particle size and greater viscosity.

The objective of this particular study was to recover valuable metals from waste plasma display panels using high energy ball milling with subsequent acid dissolution. Dissolution of milled (PDP) powder was studied in HCl, HNO3, and H2SO4 acidic solutions. The effects of dissolution acid, temperature, time, and PDP scrap powder to acid ratio on the leaching process were investigated and the most favorable conditions were found: (1) valuable metals (In, Ag, Mg) were recovered from PDP powder in a mixture of concentrated hydrochloric acid (HCl:H2O = 50:50); (2) the optimal dissolution temperature and time for the valuable metals were found to be 60°C and 30 min, respectively; (3) the ideal PDP scrap powder to acid solution ratio was found to be 1:10. The proposed method was applied to the recovery of magnesium, silver, and indium with satisfactory results.

In the present work, we have prepared Bi2Te3 nanostructures with different morphologies such as nano-spherical, nanoplates and nanoflakes obtained using various surfactant additions (EG, PVP, and EDTA) by a hydrothermal method. The shape of the nanoparticles can be controlled by addition of surfactants. The samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that the minority BiOCl phase disappears after maintained pH at 10 with EG as surfactant. SEM bulk microstructure reveals that the sample consists of fine and coarse grains. Temperature dependence of thermoelectric properties of the nanostructured bulk sample was investigated in the range of 300-450K. The presence of nanograins in the bulk sample exhibits a reduction of thermal conductivity and less effect on electrical conductivity. As a result, a figure of merit of the sintered bulk sample reached 0.2 at 400 K. A maximum micro Vickers hardness of 102 Hv was obtained for the nanostructured sample, which was higher than the other reported results.

In this study, p-type (GeTe)x(AgSbTe2)100−x: TAGS-x (where x = 75, 80, 85, and 90) thermoelectric materials were fabricated by a combination of gas atomization and a hot-extrusion process, and the effects of chemical composition on microstructure, thermoelectric, and mechanical properties were investigated. The extruded samples exhibited higher relative densities (> 99%), and a significant orientation degree parallel to the extrusion direction with fine and homogeneous microstructure was observed. The hardness of extruded samples was around 200-260 kgf/mm2, which indicates that they have much better mechanical properties than most other TE materials. The power factor of the extruded samples showed excellent values; the maximum power factor achieved was 3.81 × 10−3 W/mK2 for TAGS-90 at 723 K due to an effective combination of the Seebeck coefficient and electrical conductivity. [ABSTRACT FROM AUTHOR]

In this study, a modified hydrothermal method is reported for the preparation of Sb2Te3 and Bi0.5Sb1.5Te3 nanoplates and their bulk samples was prepared by spark plasma sintering ( SPS). The crystal structure, morphology, and thermoelectric properties were investigated. The microstructure results indicate that the bulk samples consisted nanograins after SPS. The presence of nanograins, high Seebeck coefficient (181 μV/K), high electrical conductivity (763 Ω−1 cm−1), and low thermal conductivity (1.15 W/mK) has been achieved in Sb2Te3 nanoplate bulk samples. As a result, the dimensionless thermoelectric figure of merit ( ZT) of 0.55 at 400 K was achieved. Moreover, the peak ZT shifted to higher temperature compared with other reported results found in literature. [ABSTRACT FROM AUTHOR]

The objective of this particular study was to recover valuable metals from waste plasma display panels using high energy ball milling with subsequent acid dissolution. Dissolution of milled (PDP) powder was studied in HCl, HNO3, and H2SO4 acidic solutions. The effects of dissolution acid, temperature, time, and PDP scrap powder to acid ratio on the leaching process were investigated and the most favorable conditions were found: (1) valuable metals (In, Ag, Mg) were recovered from PDP powder in a mixture of concentrated hydrochloric acid (HCl:H2O = 50:50); (2) the optimal dissolution temperature and time for the valuable metals were found to be 60°C and 30 min, respectively; (3) the ideal PDP scrap powder to acid solution ratio was found to be 1:10. The proposed method was applied to the recovery of magnesium, silver, and indium with satisfactory results. [ABSTRACT FROM AUTHOR]

In the present work, we have prepared Bi2Te3 nanostructures with different morphologies such as nano-spherical, nanoplates and nanoflakes obtained using various surfactant additions (EG, PVP, and EDTA) by a hydrothermal method. The shape of the nanoparticles can be controlled by addition of surfactants. The samples were characterized by x-ray diffraction (XRD) and scanning electron microscopy (SEM). It is found that the minority BiOCl phase disappears after maintained pH at 10 with EG as surfactant. SEM bulk microstructure reveals that the sample consists of fine and coarse grains. Temperature dependence of thermoelectric properties of the nanostructured bulk sample was investigated in the range of 300-450K. The presence of nanograins in the bulk sample exhibits a reduction of thermal conductivity and less effect on electrical conductivity. As a result, a figure of merit of the sintered bulk sample reached 0.2 at 400 K. A maximum micro Vickers hardness of 102 Hv was obtained for the nanostructured sample, which was higher than the other reported results. [ABSTRACT FROM AUTHOR]

In the present work, Cu and Ni nanofluids were synthesized using the pulsed wire evaporation (PWE) method in the different aqueous medias, namely (ethanol and ethylene glycol), and the effects of the aqueous media on the dispersion state, stability, and particle size of nanoparticles were studied. The size and morphology of synthesized nano-particles were investigated by transmission electron microscopy (TEM). Also, the dispersion stability of the nanofluids was evaluated by turbiscan analysis. The TEM results showed that the nano-particles were spherical in shape, and the average particle size was below 100 nm. The average particle size of the Cu nano-particles was smaller than that of Ni, which was attributed to a difference in the specific sublimation energy of the elements. Moreover, ethylene glycol (EG) exhibited higher suspension stability than ethanol. Finally, the dispersion stability of Cu@EG displayed the highest value due to lower particle size and greater viscosity. [ABSTRACT FROM AUTHOR]

Manufacturing an economically viable, efficient commercial thermoelectric (TE) module is essential for power generation and refrigeration. However, mediocre TE properties, lack of good mechanical stability of the material, and significant difficulties involved in the manufacturing of large-scale powder as well as bulk samples hinder the potential applications of the modules. Herein, an economically feasible single-step water atomization (WA) is employed to synthesize BST powder (2 kg) by Cu doping within a short time and consolidated into large-scale bulk samples (500 g) for the first time with a diameter of 50 mm and a thickness of about 40 mm using spark plasma sintering (SPS). The incorporation of Cu into BST greatly boosts the carrier concentration, leading to a significant increase in electrical conductivity, and inhibits the bipolar thermal conductivity by 73%. Synchronously, the lattice contribution (κ L ) is greatly reduced by the effective scattering of phonons by comprising fine-grain boundaries and point defects. Therefore, the peak ZT is shifted to the mid-temperature range and obtained a maximum of ∼1.31 at 425 K and a ZT ave of 1.24 from 300 to 500 K for the BSTCu 0.05 sample, which are considerably greater than those of the bare BST sample. Moreover, the maximum compressive mechanical strength of large-size samples manufactured by the WA-SPS process is measured as 102 MPa, which is significantly higher than commercial zone melting samples. The thermoelectric module assembled with WA-SPS-synthesized BSTCu 0.05 and commercial n-type BTS material manifests an outstanding cooling performance (-19.4 °C), and a maximum output power of 6.91 W is generated at Δ T ∼ 200 K. These results prove that the BSTCu x samples are eminently suitable for the fabrication of industrial thermoelectric modules.