Achieving synergistic performance through highly compacted microcrystalline rods induced in Mo doped GeTe based compounds

Imam, Safdar; Bayikadi, Khasim Saheb; Ubaid, Mohammad; Ranganayakulu, V. K.; Devi, S. Indra; Pujari, Bhalchandra S.; Chen, Yang‐Yuan; Chen, Li‐Chyong; Chen, Kuei‐Hsien; Lin, Feng Li

doi:10.1016/j.mtphys.2021.100571

Cited by 6 publications

(3 citation statements)

References 76 publications

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“…[4,5] The Seebeck coefficient, electrical conductivity, and electronic thermal conductivity are strongly coupled with each other through the carrier concentration, so an optimal carrier concentration is important for achieving high thermoelectric performance. [6,7] In addition, the lattice thermal conductivity (κ L ) is a relatively independent parameter [8][9][10] and can be suppressed via grain boundaries, [11,12] point defects, [13][14][15] and dislocations [16][17][18] for phonon scattering.…”

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confidence: 99%

Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂

Zhang

Yao

Wang

et al. 2022

Adv Funct Materials

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Alloying scattering of phonons is particularly effective in reducing the thermal conductivity. The alloying model considers the mass and strain fluctuations but the substitutional atoms are assumed to be positioned at the ideal lattice point, i.e., without lattice distortion. In the real case, the existence of the lattice distortion in the alloy is inevitable, and it should have an additional contribution to the phonon scattering. Such an effect, however, is usually ignored and can be partially ascribed to the difficulty of experimentally identifying and quantifying the lattice distortion. In this work, significant distortion of the crystal lattice is directly observed by the scanning transmission electron microscopy in YbCd 2 Sb 2 with multiple elements alloying. These results show that the plane distance of adjacent Ytterbium atoms along the direction b fluctuates in the range between 0.34 and 0.46 nm, a distortion from ≈−11.7% to ≈16.0%. The lattice distortion plays a remarkable role in phonon scattering and substantially reduces the lattice thermal conductivity to ≈0.45 Wm -1 K -1 at 700 K. As a result, a peak zT of ≈1.4 is achieved in (Yb 0.9 Mg 0.1 ) Cd 1.2 Mg 0.4 Zn 0.4 Sb 2 . These results indicate that tuning the lattice distortion can be a promising strategy for enhancing thermoelectric performance.

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confidence: 99%

Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂

Zhang

Yao

Wang

et al. 2022

Adv Funct Materials

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“…Because Te is easily volatilized, the substrate temperature T S is a key growth parameter. In this study, GeTe thin films were grown in the relatively low T S range (473–593 K) compared with the bulk case (773–850 K − ). The GeTe targets were fabricated in the following process.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…These defects can supply an extra number of carriers or enhance carrier scattering rate, degrading S and σ, respectively. For example, in GeTe, − known as one of the promising TE materials, controlling the point defects is the most important because the generation of Ge vacancy V Ge (acceptor) with low formation energy leads to an extra amount of carrier concentration p (∼10 21 cm –3 ), decreasing S . A lot of studies have attempted to overcome this crucial issue by adding the elements, preventing the generation of V Ge . − On the other hand, κ was drastically reduced by various scattering centers in polycrystalline GeTe. − However, the polycrystalline grain boundary with random crystal orientation can be detrimental to carrier transport because of its high carrier scattering rate.…”

Section: Introductionmentioning

confidence: 99%

Boosting Thermoelectric Performance in Epitaxial GeTe Film/Si by Domain Engineering and Point Defect Control

Ishibe

Komatsubara

Ishikawa

et al. 2023

ACS Appl. Mater. Interfaces

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This study demonstrates a simultaneous realization of ultralow thermal conductivity and high thermoelectric power factor in epitaxial GeTe thin films/Si substrates by a combination of the interface introduction by domain engineering and the suppression of Ge vacancy generation by point defect control. We formed epitaxial Te-poor GeTe thin films having low-angle grain boundaries with a misorientation angle close to 0° or twin interfaces with a misorientation angle close to 180°. The control of interfaces and point defects gave rise to ultralow lattice thermal conductivity of ∼0.7 ± 0.2 W m–1 K–1. This value was the same in the order of magnitude as the theoretical minimum lattice thermal conductivity of ∼0.5 W m–1 K–1 calculated by the Cahill–Pohl model. At the same time, the GeTe thin films exhibited a high thermoelectric power factor because of the suppression of Ge vacancy generation and a small contribution of grain boundary carrier scattering. The outstanding combined technique of domain engineering and point defect control can be a great approach for developing high-performance thermoelectric films.

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Trends in GeTe Thermoelectrics: From Fundamentals to Applications

Li,

Shi,

Chen

2024

Adv Funct Materials

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Germanium telluride (GeTe) with ultrafast ferroelectric transition, Rashba‐like electronic transport, and anomalous phonon anharmonicity are historically studied for potential memorizing and thermoelectric applications. Due to recent breakthroughs in spintronics, valleytronics, orbitronics, pre‐eminent GeTe thermoelectrics have re‐attracted enormous interest from both academia and industries, with increasing reports of significant figure‐of‐merit over 2.7 and the maximum efficiency of up to 17.0%. Here, the emerging trends in advancing GeTe thermoelectrics, starting from fundamentals of phase transformation, crystal structure, bonding mechanisms, and transport characteristics, with a highlight on the roles of Ge_4s2 lone pairs, are timely overviewed. Technical insights in synthesis, characterization, property measurement, and computation are then summarized. After that, several innovative strategies for increasing the figure‐of‐merit, including entropy engineering, nanostructuring, and hybridization, which will further benefit near‐room‐temperature and n‐type performance, are examined. Moreover, high‐density and high‐efficiency devices with broad working temperatures are discussed as a result of rational configurational and interfacial design. In the end, perspective remarks on the challenges and outlook envisaging for next‐generation GeTe thermoelectrics, which will play a prominent role in future energy and environmental landscapes, are provided.

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Achieving synergistic performance through highly compacted microcrystalline rods induced in Mo doped GeTe based compounds

Cited by 6 publications

References 76 publications

Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂

Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂

Boosting Thermoelectric Performance in Epitaxial GeTe Film/Si by Domain Engineering and Point Defect Control

Trends in GeTe Thermoelectrics: From Fundamentals to Applications

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Achieving synergistic performance through highly compacted microcrystalline rods induced in Mo doped GeTe based compounds

Cited by 6 publications

References 76 publications

Achieving High Thermoelectric Performance in Severely Distorted YbCd2Sb2

Achieving High Thermoelectric Performance in Severely Distorted YbCd2Sb2

Boosting Thermoelectric Performance in Epitaxial GeTe Film/Si by Domain Engineering and Point Defect Control

Trends in GeTe Thermoelectrics: From Fundamentals to Applications

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Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂

Achieving High Thermoelectric Performance in Severely Distorted YbCd₂Sb₂