Solid solution formation in Mg2(Si,Sn) and shape of the miscibility gap

Yasseri, Mohammad; Sankhla, Aryan; Kamila, Hasbuna; Orenstein, Rachel; Truong, Dao Y Nhi; Farahi, Nader; Boor, Johannes de; Mueller, E.

doi:10.1016/j.actamat.2019.11.054

Cited by 36 publications

(35 citation statements)

References 40 publications

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“…The sintering temperature was adjusted according to the sample composition 36 and is listed together with further parameters in Table 1. The material system is well known for a reported miscibility gap with disputed borders 39 , but we showed recently that single phase synthesis is feasible 40 in agreement with other experimental reports [41][42] . The apparent discrepancy between experimental findings and calculation results might be related to a straininduced suppression of the miscibility gap 43 .…”

Section: Methodssupporting

confidence: 90%

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

2020

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Tailoring and further optimization of thermoelectric materials requires detailed knowledge and understanding of the thermal and electrical transport in these materials. One crucial parameter is the density of states effective mass, which governs both the electrical conductivity as well as the Seebeck coefficient. We investigate the density of states effective mass for magnesium silicide, magnesium stannide and their solid solutions using experimental data as well as Density Functional Theory in a Generalized Gradient Approach; for the solid solutions, the Special Quasi-Random Structures approach is employed. Extracting the effective mass directly from the calculated densities of states we can show an approximatively linear decrease from Mg2Si to Mg2Sn and consistency with respect to the chosen cell size. The experimental data, obtained assuming a single parabolic band model, shows good agreement with the calculated data for Mg2Sn and Sn-rich solid solutions, but a clear difference at the Si-rich side. The lower effective mass for the Sn-rich solid solutions indicates that the electronic properties are expected to be superior to those of Si-rich solid solutions as long as minority carrier effects can be neglected.

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Section: Methodssupporting

confidence: 90%

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

2020

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“…Remnant inhomogeneity (Si‐rich compositions) from the ball‐milling step in samples with different x required different temperatures and holding durations to dissolve into the matrix by interdiffusion to form a uniform material. Details on homogenization of, e.g., for a Mg 2 Si 0.5 Sn 0.5 matrix and investigation of its microstructure by scanning electron microscope (SEM) can be found in our previous work [21a,22]. Furthermore, Sn‐rich samples were less stable against Mg loss at high temperatures than Si‐rich samples .…”

Section: Methodsmentioning

confidence: 99%

Raman Spectroscopic Study of the Optical Phonons of Mg₂Si_1−xSn_x Solid Solutions

Yasseri

Schüpfer

Chen

et al. 2020

Physica Rapid Research Ltrs

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Mg2Si1−xSnx solid solutions are prepared in the composition range from x = 0 to 1 by mechanical alloying using high‐energy ball milling followed by direct‐current sintering at 600–800 °C. X‐ray diffraction analysis confirms that the samples obtained are uniform solid solutions. Raman spectroscopy shows two first‐order phonon Raman bands and a distribution of Raman signals due to second‐order phonon Raman scattering. The first‐order Raman bands are assigned to the nondegenerate Raman‐forbidden F1u (LO) mode and the triply degenerate Raman‐allowed F2g mode. Both modes exhibit a linear shift of the phonon frequency with a composition showing a clear one‐mode behavior for this solid solution. The findings are discussed in the context of existing theories for the occurrence of the one‐mode or two‐mode behavior of phonons in solid solutions.

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“…One key issue underlying the usage of this strategy is whether the solid solution can be formed in a full composition range (or whether there is a miscibility gap). The miscibility gap occurs in several TE systems, such as Mg 2 Si 1- x Sn x [ 152 – 154 ], Ti 1- x Zr x NiSn [ 155 , 156 ], and Ti 1- x Zr x CoSb [ 157 , 158 ]. Luckily, there seems no miscibility gap in the Mg 3 Sb 2- x Bi x system [ 33 , 47 , 73 ].…”

Section: Optimization Of Te Propertiesmentioning

confidence: 99%

High-Performance Mg ₃ Sb _{2-
x} Bi _x Thermoelectrics: Progress and Perspective

Zhao

et al. 2020

Research

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Since the first successful implementation of n-type doping, low-cost Mg3Sb2-xBix alloys have been rapidly developed as excellent thermoelectric materials in recent years. An average figure of merit zT above unity over the temperature range 300–700 K makes this new system become a promising alternative to the commercially used n-type Bi2Te3-xSex alloys for either refrigeration or low-grade heat power generation near room temperature. In this review, with the structure-property-application relationship as the mainline, we first discuss how the crystallographic, electronic, and phononic structures lay the foundation of the high thermoelectric performance. Then, optimization strategies, including the physical aspects of band engineering with Sb/Bi alloying and carrier scattering mechanism with grain boundary modification and the chemical aspects of Mg defects and aliovalent doping, are extensively reviewed. Mainstream directions targeting the improvement of zT near room temperature are outlined. Finally, device applications and related engineering issues are discussed. We hope this review could help to promote the understanding and future developments of low-cost Mg3Sb2-xBix alloys for practical thermoelectric applications.

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Solid solution formation in Mg2(Si,Sn) and shape of the miscibility gap

Cited by 36 publications

References 40 publications

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Raman Spectroscopic Study of the Optical Phonons of Mg₂Si_1−xSn_x Solid Solutions

High-Performance Mg ₃ Sb _{2-
x} Bi _x Thermoelectrics: Progress and Perspective

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Solid solution formation in Mg2(Si,Sn) and shape of the miscibility gap

Cited by 36 publications

References 40 publications

Density of States Effective Mass for p-Type Mg2Si–Mg2Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Density of States Effective Mass for p-Type Mg2Si–Mg2Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Raman Spectroscopic Study of the Optical Phonons of Mg2Si1−xSnx Solid Solutions

High-Performance Mg 3 Sb 2- x Bi x Thermoelectrics: Progress and Perspective

Contact Info

Product

Resources

About

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Density of States Effective Mass for p-Type Mg₂Si–Mg₂Sn Solid Solutions: Comparison between Experiments and First-Principles Calculations

Raman Spectroscopic Study of the Optical Phonons of Mg₂Si_1−xSn_x Solid Solutions

High-Performance Mg ₃ Sb _{2-
x} Bi _x Thermoelectrics: Progress and Perspective