Effect of Anomalous Crystal Structure of Iron Aluminides Fe&lt;sub&gt;2&lt;/sub&gt;Al&lt;sub&gt;5&lt;/sub&gt; and Fe&lt;sub&gt;4&lt;/sub&gt;Al&lt;sub&gt;13&lt;/sub&gt;: Low Phonon Thermal Conductivity and Potentiality as Thermoelectric Materials

Tobita, Kazuki; Sato, Naoki; Kitahara, Koichi; Takagiwa, Yoshiki; Kimura, Kaoru

doi:10.2320/matertrans.mf201607

Cited by 19 publications

(8 citation statements)

References 12 publications

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“…The corresponding atomic volume of 13.0 Å 3 /atom was denser than the 13.8 Å 3 /atom of a-FeAl 2 [31], which indicated that t-FeAl 2 became more stable than a-FeAl 2 as the pressure increased. In the assigned space group I4/mmm, only the z position of Al atoms was refined to be z = 0.3429 (3).…”

Section: Resultsmentioning

confidence: 99%

“…Iron aluminides are thus favorable as thermoelectric materials because of their abundance and environmentally benign constituent elements. We previously investigated the thermoelectric properties of triclinic FeAl 2 (a-FeAl 2 , space group P−1), Fe 2 Al 5 and Fe 4 Al 13 in the Al-rich part of Fe-Al binary systems, and found that these materials have a low κ ph of 0.82 W/mK (for Fe 4 Al 13 ) because of their complex and disordered crystal structures [3]. However, the maximum ZT remained at 0.03 (for Fe 4 Al 13 ) because of its low S of~30 µV/K.…”

Section: Introductionmentioning

confidence: 99%

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Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂

Tobita

Kitahara

Katsura

et al. 2019

Science and Technology of Advanced Materials

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Tetragonal FeAl 2 is a high-pressure phase and is predicted to exhibit semiconductor-like behavior. We investigated the pressure and temperature synthesizing conditions of tetragonal FeAl 2 , supported by in situ X-ray diffractions, using synchrotron radiation during heating the sample under a pressure of 20 GPa. Based on the determined optimal conditions, we synthesized the bulk polycrystalline samples of tetragonal FeAl 2 at 7.5 GPa and 873 K, using a multi-anvil press and measured its thermoelectric properties. The Seebeck coefficient of tetragonal FeAl 2 showed a large negative value of -105 μV/K at 155 K and rapidly changed to a positive value of 75 μV/K at 400 K. Although these values are the largest among those of Fe-Al alloys, the maximum power factor remained at 0.41 mW/mK 2 because the carrier concentration was not tuned. A comparison of the Gibbs free energy of tetragonal FeAl 2 , triclinic FeAl 2 and FeAl+Fe 2 Al 5 revealed that tetragonal FeAl 2 became unstable as the temperature increased, because of its smaller contribution of vibrational entropy.Temperature, T / K Pressure, P / GPa ARTICLE HISTORY

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂

Tobita

Kitahara

Katsura

et al. 2019

Science and Technology of Advanced Materials

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“…In addition, the content of Zn in the reaction layer increased from the center to the edge. From the result of the quantitative analysis shown in Table 1, the bright gray phase in the interfacial reaction layer was inferred to be Fe 4 Al 13 [32]. The formation of the similar Fe-Al IMC layer was reported in the dissimilar aluminum/steel joint fabricated via a refilled FSSW [33].…”

Section: Microstructures Of Jointsmentioning

confidence: 69%

Microstructure and Fatigue Behaviors of Dissimilar A6061/Galvannealed Steel Joints Fabricated by Friction Stir Spot Welding

et al. 2021

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The microstructures, tensile shear properties, and tensile shear fatigue properties of dissimilar A6061/Galvannealed steel joints fabricated by friction stir spot welding (FSSW) were investigated. Fe4Al13 phases form as the intermetallic compound (IMC) layer at the joint interface between the A6061 matrix and the galvannealed layer consisting of FeZn7, Fe, and Zn. At the edge of the joint, the stirred layer in which the A6061 matrix and the galvannealed layer are stirred also forms. Moreover, the solidified part of the residual melt discharged from the joint area forms at the outer peripheries of the joint. In this study, FSSW was conducted for two total welding durations: 9 and 10 s. Although the thickness of the remaining A6061 sheet in the welded area decreased with an increase in the welding time, the effects of the total welding time on tensile shear and tensile shear fatigue properties were negligible. A fatigue fracture occurred in the A6061 matrix and at the joint interface at the high cycle fatigue region and the low cycle fatigue region, respectively. In the case of the interfacial fracture, the crack was generated in the solidified part of the residual melt or at the interface between the solidified part and the stirred layer.

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“…In recent years, several structural origins bringing intrinsically low κlat like complex crystal structure, [11][12][13][14][15][16][17][18][19][20] resonant bonding, [21][22][23] stereochemically active lone-pair electrons, [24][25][26][27][28][29][30][31] rattling and its reminiscent anharmonic vibration, [30,[32][33][34][35][36][37][38][39][40][41][42] superionic transition, [43][44][45][46][47] partial occupancy, [48,49] and bonding heterogeneity [27,40,[50][51][52][53][54][55][56] have been unveiled. Among these, we focus on the bonding h...…”

Section: Introductionmentioning

confidence: 99%

Bonding Heterogeneity in Mixed-Anion Compounds Realizes Ultralow Lattice Thermal Conductivity

Sato¹,

Kuroda²,

Nakamura³

et al. 2021

Preprint

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<a>Crystalline materials with intrinsically low lattice thermal conductivity (</a>κlat) pave the way towards high performance in various energy applications, including thermoelectrics. Here we demonstrate a strategy to realize ultralow κlat using mixed-anion compounds. Our calculations reveal that locally distorted structures in chalcohalides MnPnS2Cl (Pn = Sb, Bi) derives a bonding heterogeneity, which in turn causes a peak splitting of the phonon density of states. This splitting induces a large amount of scattering phase space. Consequently, κlat of MnPnS2Cl is significantly lower than that of a single-anion sulfide CuTaS3 with a similar crystal structure. Experimental κlat of MnPnS2Cl takes an ultralow value of about 0.5 W m−1 K−1 at 300 K. Our findings will encourage the exploration of thermal transport in mixed-anion compounds, which remain a vast unexplored space, especially regarding unexpectedly low κlat in lightweight materials derived from the bonding heterogeneity.

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Effect of Anomalous Crystal Structure of Iron Aluminides Fe<sub>2</sub>Al<sub>5</sub> and Fe<sub>4</sub>Al<sub>13</sub>: Low Phonon Thermal Conductivity and Potentiality as Thermoelectric Materials

Cited by 19 publications

References 12 publications

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂

Microstructure and Fatigue Behaviors of Dissimilar A6061/Galvannealed Steel Joints Fabricated by Friction Stir Spot Welding

Bonding Heterogeneity in Mixed-Anion Compounds Realizes Ultralow Lattice Thermal Conductivity

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Effect of Anomalous Crystal Structure of Iron Aluminides Fe<sub>2</sub>Al<sub>5</sub> and Fe<sub>4</sub>Al<sub>13</sub>: Low Phonon Thermal Conductivity and Potentiality as Thermoelectric Materials

Cited by 19 publications

References 12 publications

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl2

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl2

Microstructure and Fatigue Behaviors of Dissimilar A6061/Galvannealed Steel Joints Fabricated by Friction Stir Spot Welding

Bonding Heterogeneity in Mixed-Anion Compounds Realizes Ultralow Lattice Thermal Conductivity

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Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂

Phase stability and thermoelectric properties of semiconductor-like tetragonal FeAl₂