Enhanced average thermoelectric properties of n‑type Mg3Sb2 based materials by mixed-valence Ni doping

Zhu, Wenyan; Zheng, Pingping; Shao, Yaoming; Fang, Wenqiang; Wu, Honghui; Si, Jianxiao

doi:10.1016/j.jallcom.2022.166598

Cited by 8 publications

(6 citation statements)

References 30 publications

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“…28 Similarly, our work based on the defect formation energy calculations about interstitial insertion under Mg-rich and -poor conditions reveals that interstitial Ni exhibits the lowest formation energy, as shown in Figure 7c. Some studies suggest that Ni doping will replace Mg sites, 32 which conflicts with our conclusion. However, the Ni formation energy shows that Ni is always in the interstitial site.…”

Section: Thermal Stabilitycontrasting

confidence: 98%

Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Sun

et al. 2023

ACS Appl. Mater. Interfaces

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N-type Mg3Sb2 is attracting increasing focus for its outstanding room-temperature (RT) thermoelectric (TE) performance; however, achieving reliable n-type conduction remains challenging due to negatively charged Mg vacancies. Doping with compensation charges is generally used but does not fundamentally resolve the high intrinsic activity and easy formation of Mg vacancies. Herein, a robust structural and thermoelectric performance is obtained by manipulating Mg intrinsic migration activity by precisely incorporating Ni at the interstitial site. Density functional theory (DFT) indicates that a strong performance originates from a significant thermodynamic preference for Ni occupying the interstitial site across the complete Mg-poor to -rich window, which dramatically promotes the Mg migration barrier and kinetically immobilizes Mg. As a result, the detrimental vacancy-associated ionized scattering is eliminated with a leading room-temperature ZT up to 0.85. This work reveals that interstitial occupation in Mg3Sb2-based materials is a novel approach promoting both structural and thermoelectric performance.

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Section: Thermal Stabilitycontrasting

confidence: 98%

Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Sun

et al. 2023

ACS Appl. Mater. Interfaces

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“…Briefly, the Hall carrier concentration of x CrTe/MBA composites in our work is comparable to those of Se-doped Mg 3 (Bi, Sb) 2 , Y-doped Mg 3 SbBi, La-doped Mg 3.2 Bi 1.5 Sb 0.5 , and Te-doped Mg 3 Sb 2 . A high μ H around 209 cm 2 ·V –1 ·s –1 at room temperature can be realized in present work, which is higher than those reported Mg 3 Bi 2 -based samples at the same carrier concentration. ,,, It is evident that, compared to the serious deterioration of mobility caused by traditional homogeneous magnetic-element doping, , the spatially confined magnetic ordered structure may yield higher carrier mobility.…”

Section: Resultssupporting

confidence: 59%

“…37 A high μ H around 209 cm 2 •V −1 •s −1 at room temperature can be realized in present work, which is higher than those reported Mg 3 Bi 2 -based samples at the same carrier concentration. 25,55,63,64 It is evident that, compared to the serious deterioration of mobility caused by traditional homogeneous magnetic-element doping, 43,44 the spatially confined magnetic ordered structure may yield higher carrier mobility.…”

Section: Microstructure Analysis Of Xcrte/mba Compositesmentioning

confidence: 99%

“…As for n-type Mg 3 (Sb, Bi) 2 -based systems, although magnetic elements, such as Fe, Co, and Ni, have already been used as dopants to improve the thermoelectric performance, , systematic investigations on the effect of magnetism have rarely been performed. In this work, CrTe, an n-type ferromagnetic metal with Curie temperature ( T C ) ∼ 340 K, was chosen as the spatially confined magnetic functional units to optimizing the near-room-temperature TE performance of the n-type Mg 3.4 Bi 1.5 Sb 0.5 matrix, by virtue of its magnetic transition and possible lower work function.…”

Section: Introductionmentioning

confidence: 99%

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Improving Thermoelectric Performance of n-Type Mg₃Bi₂-Based Materials by Introducing a Spatially Confined Magnetic Ordered Structure

Huang

Luo

et al. 2023

ACS Appl. Energy Mater.

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Magnetism, which relates to the spin and orbital degrees of freedom, is recently considered as the fountain of some potentially paradigm-changing mechanisms to decouple the adversely interdependent thermal and electrical transport parameters of thermoelectric materials. Herein, we construct a thermoelectro-magnetic coupling thermoelectric system by introducing a spatially confined ferromagnetic CrTe secondary phase into the Mg 3.4 Bi 1.5 Sb 0.5 (MBA) matrix. It is found that the spatially confined magnetic ordered structure, CrTe, can act as electron injection units to substantially promote the carrier concentration of the MBA matrix without deteriorating the carrier mobility, which usually occurs in the uniform magnetic-element doping systems. An increase in the Seebeck coefficient of the CrTe-incorporated system due to the magnetic phase transition was also acknowledged, which further confirms the advantage of introducing spin and orbital degrees of freedom into the thermoelectric materials. Combined with the enhanced phonon scattering by the second phase, a maximum zT value ∼1.1 was achieved in the 0.35 wt % CrTe/Mg 3.4 Bi 1.5 Sb 0.5 composite at 587 K.

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“…The peak at 145 cm −1 (141 cm −1 for the ntype sample) was supposed to be a Raman-forbidden transmission; however, it has also been observed in different reports such as for the undoped, the Cu, Ag, and Cu−Ag codoped polycrystalline 47 and single-crystalline Mg 3 Sb 2 48 and Mg 3 Sb 2 compounds covered on the graphene nanosheets, 49 and so on. 50,51 We propose that the observation of this unexpected Raman peak is due to the detection of the zoneedged acoustic phonon modes 52 (the acoustic branches extending to the A-point). Further investigation on the resonance Raman measurements is currently underway.…”

Section: ■ Results and Discussionmentioning

confidence: 90%

Identifying the Point Defects in Single-Crystalline Mg₃Sb₂

Yao

Zhi

et al. 2023

Chem. Mater.

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Point defects play a critical role in the transport properties of Mg 3 Sb 2based thermoelectric materials. However, the determination of point defects is rather challenging. Herein, Mg 3 Sb 2 single crystals were prepared by the self-flux method with the Sb flux (p-type sample) and Mg flux (n-type sample). The crystal structure as well as the atomic occupancy parameters of these samples were determined by single-crystal and synchrotron powder X-ray diffractions. Comparison between the experimental and calculated Fourier electron density maps generated by single-crystal data indicates the existence of Mg interstitials [1/3, 2/3, 0.38(3)] and vacancies at the Mg2 sites [2/3, 1/3, 0.8653(3)] in the n-type sample and Mg vacancies at both the Mg1 and Mg2 sites in the p-type sample. In addition, differences in the peak positions and intensities of the two types of Mg−Sb vibration modes in Raman spectra were observed between different Mg 3 Sb 2 crystals, which suggests that point defects can impact the vibration modes.

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Enhanced average thermoelectric properties of n‑type Mg3Sb2 based materials by mixed-valence Ni doping

Cited by 8 publications

References 30 publications

Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Improving Thermoelectric Performance of n-Type Mg₃Bi₂-Based Materials by Introducing a Spatially Confined Magnetic Ordered Structure

Identifying the Point Defects in Single-Crystalline Mg₃Sb₂

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Enhanced average thermoelectric properties of n‑type Mg3Sb2 based materials by mixed-valence Ni doping

Cited by 8 publications

References 30 publications

Realizing Excellent Structural and Thermoelectric Performance in Mg3Sb2-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Realizing Excellent Structural and Thermoelectric Performance in Mg3Sb2-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Improving Thermoelectric Performance of n-Type Mg3Bi2-Based Materials by Introducing a Spatially Confined Magnetic Ordered Structure

Identifying the Point Defects in Single-Crystalline Mg3Sb2

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Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Realizing Excellent Structural and Thermoelectric Performance in Mg₃Sb₂-Based Alloys by Manipulating Mg Intrinsic Migration Kinetics with Interstitial Ni Doping

Improving Thermoelectric Performance of n-Type Mg₃Bi₂-Based Materials by Introducing a Spatially Confined Magnetic Ordered Structure

Identifying the Point Defects in Single-Crystalline Mg₃Sb₂