Thermoelectric properties of type-VIII clathrate Ba8Ga16Sn30 doped with Cu

Saiga, Yasuhiro; Du, Baoli; Deng, Shukang; Kajisa, Kousuke; Takabatake, T.

doi:10.1016/j.jallcom.2012.05.049

Cited by 91 publications

(69 citation statements)

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“…Pursuing higher ZT for higher efficiency has been the focus by mainly reducing the thermal conductivity. In this paper, we point out, for a given ZT, higher power factor (S 2 σ) should be pursued for achieving more power because power is determined by (20), and p-type Zn 4-δ Sb 3 (21) have higher average ZT values below 400°C. However, the low power factors make them unsuitable for power generation applications below 400°C.…”

Section: ·Kmentioning

confidence: 99%

n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation

Liu

Kim

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

198

131

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Thermoelectric power generation is one of the most promising techniques to use the huge amount of waste heat and solar energy. Traditionally, high thermoelectric figure-of-merit, ZT, has been the only parameter pursued for high conversion efficiency. Here, we emphasize that a high power factor (PF) is equivalently important for high power generation, in addition to high efficiency. A new n-type Mg 2 Sn-based material, Mg 2 Sn 0.75 Ge 0.25 , is a good example to meet the dual requirements in efficiency and output power. It was found that Mg 2 Sn 0.75 Ge 0.25 has an average ZT of 0.9 and PF of 52 μW·cm ·K−2 over the temperature range of 25-450°C, a peak ZT of 1.4 at 450°C, and peak PF of 55 μW·cm·K −2 at 350°C. By using the energy balance of one-dimensional heat flow equation, leg efficiency and output power were calculated with T h = 400°C and T c = 50°C to be of 10.5% and 6.6 W·cm −2 under a temperature gradient of, respectively.thermoelectrics | magnesium | tin | power factor | output power T hermoelectric power generation from waste heat is attracting more and more attention. Potential fuel efficiency enhancement by recovering the waste heat is beneficial for automobiles and many other applications (1, 2). In addition, solar thermoelectric generator provides an alternative route to convert solar energy into electrical power besides the photovoltaic conversion (3). Thermoelectric generator (TEG) can be regarded as a heat engine using electrons/holes as the energy carrier. The conversion efficiency of a TEG is related to the Carnot efficiency and the material's average thermoelectric figure of merit ZT (4):where ZT = (S 2 σ/κ)T, and S, σ, κ, and T are Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature, respectively. Pursuing high ZT has been the focus of the entire thermoelectric community by applying various phonon engineering via nanostructuring approaches to reduce the thermal conductivity (5-7), or by exploring new compounds with intrinsically low thermal conductivity, such as compounds having complex crystalline structure, local rattlers, liquid-like sublattice, and highly distorted lattice (8-11). However, for practical applications, efficiency is not the only concern, and high output power density is as important as efficiency when the capacity of the heat source is huge (such as solar heat), or the cost of the heat source is not a big factor (such as waste heat from automobiles, steel industry, etc.). The output power density ω is defined as the output power W divided by the cross-sectional area A of the leg, i.e., ω = W/A, which is related to power factor PF = S 2 σ by the following:Eq. 2 contains two main parts: square of the temperature difference divided by leg length, and material power factor PF = S 2 σ.Clearly, to achieve higher power density for a given heat source, we have to either increase the power factor PF or decrease the leg length. However, decreasing the leg length could cause severe consequences such as increase of large heat flux that will incr...

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Section: ·Kmentioning

confidence: 99%

n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation

Liu

Kim

Chen

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

198

131

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“…3,4 Clathrates are therefore expected to be high-efficiency thermoelectric materials. 2, [5][6][7][8][9] In addition, they do not contain toxic elements.…”

Section: Introductionmentioning

confidence: 99%

“…Takabatake et al investigated the physical properties, including the thermoelectric properties, of single crystals. 9,17,18 They found that a single crystal of Ba 8 Ga 16 Sn 30 doped with Cu had a ZT value as high as 1.45 at 500 K (Ref. 9).…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Thermoelectric and transport properties of sintered n-type K8Ba16Ga40Sn96 with type-II clathrate structure

Koda

Kishimoto

Akai

et al. 2014

Journal of Applied Physics

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This clathrate had a maximum dimensionless figure-of-merit, ZT, of 0.93 at 637 K, which was slightly higher than that of 0.83 for the sintered type-VIII clathrate Ba8Ga16Sn30. We investigated the high-temperature thermoelectric properties, transport properties, electronic structures, and thermal stabilities of the clathrates. The type-II clathrate was found to be superior to the type-VIII clathrate as a thermoelectric material; it had a high thermal stability and melting point, 859 K, high mobility, 141 cm2V−1s−1 at 300 K, because of its low inertial mass, and low high-temperature lattice thermal conductivity, approximately 4 mW cm−1K−1, resulting from a larger unit cell and weaker bipolar thermal conduction. We discuss these properties in terms of the electronic structure and the differences between the two types of clathrate.

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“…Recent discoveries of several new classes of thermoelectric materials like cage-structured PGECs (phonon glass electron crystal systems) [2][3][4][5], nanostructured materials [6][7][8][9][10] and magnetic semiconductors [11][12][13] have incited a renewed interest in thermoelectric materials development. The performance of thermoelectric materials can be gauged by the figure of merit ZT = S 2 T/qj, where S, q, j and T are the Seebeck coefficient, electrical resistivity, thermal conductivity and absolute temperature, respectively.…”

Section: Introductionmentioning

confidence: 99%

Thermoelectric properties of boron carbide/HfB2 composites

Innocent

Portehault

Gouget

et al. 2017

Mater Renew Sustain Energy

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Boron carbide/hafnium diboride composites were prepared by spark plasma sintering of a mixture of hafnium diboride and boron carbide powders. Boron carbide was prepared with a 13.3 at.% composition of carbon, known as the ideal carbon content to maximize the dimensionless figure of merit. The hafnium diboride content was varied between 0 and 20% by weight, and the effect on the thermoelectric properties was studied. Addition of HfB 2 generally yielded an increase in the electrical conductivity and simultaneously a reduction in thermal conductivity, indicating it has potential as an enhancer of thermoelectric properties. However, the increase in electrical conductivity was not as large as observed in some composite systems, since HfB 2 turned out to be a poor sintering additive leading to lower relative densities, and was furthermore offset by a moderate decrease in Seebeck coefficient. For future composite design, the sintering characteristics of the additives can be concluded as an important additional parameter to be taken into account. The optimal hafnium diboride content for relatively dense samples was found to be 10 wt%, resulting in an improvement in the maximum figure of merit, up to ZT = 0.20 at 730°C.

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Thermoelectric properties of type-VIII clathrate Ba8Ga16Sn30 doped with Cu

Cited by 91 publications

References 20 publications

n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation

n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation

Thermoelectric and transport properties of sintered n-type K8Ba16Ga40Sn96 with type-II clathrate structure

Thermoelectric properties of boron carbide/HfB2 composites

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Thermoelectric properties of type-VIII clathrate Ba8Ga16Sn30 doped with Cu

Cited by 91 publications

References 20 publications

n-type thermoelectric material Mg 2 Sn 0.75 Ge 0.25 for high power generation

n-type thermoelectric material Mg 2 Sn 0.75 Ge 0.25 for high power generation

Thermoelectric and transport properties of sintered n-type K8Ba16Ga40Sn96 with type-II clathrate structure

Thermoelectric properties of boron carbide/HfB2 composites

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Product

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n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation

n-type thermoelectric material Mg ₂ Sn _0.75 Ge _0.25 for high power generation