The high-energy milling process as a synergistic approach to minimize the thermal conductivity of PbTe nanostructures

Rojas-Chávez, H.; Juárez-García, J. M.; Herrera-Rivera, R.; Flores-Rojas, E.; González-Domínguez, J. L.; Cruz‐Orea, A.; Cayetano-Castro, N.; Ávila-García, A.; Mondragón-Sánchez, M. L.

doi:10.1016/j.jallcom.2019.153167

Cited by 11 publications

(8 citation statements)

References 48 publications

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“…To avoid overheating of the apparatus at long milling times, the mill was stopped for 10 min after every 30 min of milling. 22 The as-milled samples were extracted periodically at various fixed times. After the process, the as-milled samples were washed several times with de-ionized water and dried under an Ar atmosphere for further characterization.…”

Section: Methodsmentioning

confidence: 99%

“…The HEM process was carried out for up to 5 h to trace the mechanisms of formation of the PbTe QDs under c – P – T vial conditions. To avoid overheating of the apparatus at long milling times, the mill was stopped for 10 min after every 30 min of milling . The as-milled samples were extracted periodically at various fixed times.…”

Section: Experimental Sectionmentioning

confidence: 99%

“…The effects of milling parameters, such as composition, pressure, and temperature ( c – P – T ) vial conditions developed during milling, on the composition, size, and shape of the resultant lead chalcogenide nanostructures have been comprehensively investigated. − Nonetheless, researchers still aim to obtain PbTe QDs by mechanochemical synthesis. According to previous studies, it was identified that the ORE must be suppressed during milling to obtain dispersed PbTe QDs.…”

Section: Introductionmentioning

confidence: 99%

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Oriented-Attachment- and Defect-Dependent PbTe Quantum Dots Growth: Shape Transformations Supported by Experimental Insights and DFT Calculations

et al. 2021

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High-resolution transmission electron microscopy results reveal that oriented-attachment- and defect-dependent mechanisms rule the size and shape evolution of the monodispersed PbTe quantum dots (QDs). The former is characterized by the growth of quasi-cubic PbTe QDs, which depends on both the geometric constraints imposed by the {200} facets and the defect-free lattice, while the latter one is a defect-dependent mechanism which gives way to the formation of decahedral PbTe QDs (∼6 nm). Experimentally, formaldehyde is an important parameter for the mechanochemical synthesis of monodispersed PbTe QDs, which has not been studied until now. In a theoretical context, Fukui functions reveal that Pb surface atoms are the most reactive sites toward nucleophilic attacks, and the Lowdin charge analysis shows that formaldehyde molecules tend to donate their electron pairs to Pb atoms. Besides, formaldehyde-molecule-on-PbTe adsorption energies (−4.46 to −21.16 kcal mol–1) agree with ligand–surface polar electrostatic interactions. Based on dispersion-corrected density functional theory calculations, PbTe QDs exhibited decahedral and faceted shapes. According to modified Wulff constructions, the decahedral shape is a result of (111) facets (Δγ = −2.79 meV Å–2), whereas the faceted and rounded shapes are due to the interaction of (100), (110), and (111) facets.

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Section: Methodsmentioning

confidence: 99%

Section: Experimental Sectionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Oriented-Attachment- and Defect-Dependent PbTe Quantum Dots Growth: Shape Transformations Supported by Experimental Insights and DFT Calculations

et al. 2021

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“…Point defects in the form of intrinsic lattice defects and extrinsic dopants are considered here to engineer κ vib , and to control electronic carriers, a necessity for high zT in lead chalcogenides . Processing methods like high-energy ball milling , are then used to powder the ingots while controlling the particle size and increasing internal strain by introducing microstructural defects, such as dislocations. The point defects introduced at the start will influence the defects that form during powdering.…”

Section: Introductionmentioning

confidence: 99%

Thermal Evolution of Internal Strain in Doped PbTe

et al. 2021

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Recent improvements in the efficiency of heat-toelectricity energy conversion in lead chalcogenide thermoelectrics involve reducing the thermal conductivity by incorporating large amounts of internal strain. The extent to which typical lead chalcogenide processing techniques (such as doping, ball milling, and densification) increase internal strain and dislocation density must be quantified to improve materials design. In this study, neutron powder diffraction is leveraged to evaluate the internal strain introduced by ball milling in doped and undoped powders. Doping with Na and/or Eu increases internal strain beyond ball milling alone, with the greatest increase from combining the two dopants. Strain recovery occurs in each powder above 400 K but can be suppressed by co-doping, indicating a strong dopant−dislocation interaction in this system. Therefore, high-temperature processing of PbTe powders should be avoided if high internal strain is desired. Low-temperature densification and/or rapid pressing techniques may be key to maintaining internal strain in the final pressed pellet. The diffraction peak asymmetry and correlated elastic softening measured in pressed PbTe pellets in past studies were not observed in the precursor powders measured here, suggesting that measurements of the Debye temperature on final pressed pellets are required to examine the influence of defect-induced elastic softening on thermal conductivity. This work provides key guidance for defect engineering to maximize internal strain and thermoelectric performance in PbTe thermoelectrics.

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“…[27][28][29][30][31][32][33][34] In addition, CQDs offer a tunable density of grain boundaries that can be exploited to suppress thermal transport, providing an effective approach to reducing the thermal conductivity of thin films. [26,[35][36][37][38][39] These appealing features make CQDs a promising building block for application in efficient thermoelectric generators (TEGs) operating near room temperature (RT). [40][41][42] Semiconducting CQDs have witnessed a rapid improvement in their thermoelectric performance, nearing the performance of conventional bulk thermoelectric systems based on bismuth telluride (Bi 2 Te 3 ).…”

Section: Introductionmentioning

confidence: 99%

Recent Progress in Colloidal Quantum Dot Thermoelectrics

et al. 2023

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Semiconducting colloidal quantum dots (CQDs) represent an emerging class of thermoelectric materials for use in a wide range of future applications. CQDs combine solution processability at low temperatures with the potential for upscalable manufacturing via printing techniques. Moreover, due to their low dimensionality, CQDs exhibit quantum confinement and a high density of grain boundaries, which can be independently exploited to tune the Seebeck coefficient and thermal conductivity, respectively. This unique combination of attractive attributes makes CQDs very promising for application in emerging thermoelectric generator (TEG) technologies operating near room temperature. Herein, recent progress in CQDs for application in emerging thin‐film thermoelectrics is reviewed. First, the fundamental concepts of thermoelectricity in nanostructured materials are outlined, followed by an overview of the popular synthetic methods used to produce CQDs with controllable sizes and shapes. Recent strides in CQD‐based thermoelectrics are then discussed with emphasis on their application in thin‐film TEGs. Finally, the current challenges and future perspectives for further enhancing the performance of CQD‐based thermoelectric materials for future applications are discussed.

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The high-energy milling process as a synergistic approach to minimize the thermal conductivity of PbTe nanostructures

Cited by 11 publications

References 48 publications

Oriented-Attachment- and Defect-Dependent PbTe Quantum Dots Growth: Shape Transformations Supported by Experimental Insights and DFT Calculations

Oriented-Attachment- and Defect-Dependent PbTe Quantum Dots Growth: Shape Transformations Supported by Experimental Insights and DFT Calculations

Thermal Evolution of Internal Strain in Doped PbTe

Recent Progress in Colloidal Quantum Dot Thermoelectrics

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