Experimental estimation of the Lorenz number and scattering parameter for p-type bismuth antimony telluride via multiple doping under constant temperature conditions

Asai, Jun; Bumbrungpon, Mongkol; Tsubochi, Toshiya; Kanaya, Takayuki; Tachii, Masaya; Maeda, Toshiki; Iwamoto, Toschitake; Kanda, Chika; Hasezaki, Kazuhiro

doi:10.1016/j.ceramint.2022.01.119

Cited by 2 publications

(3 citation statements)

References 55 publications

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“…This approach would typically be applied for a series of materials that have the same or similar value of L but differing magnitudes of κ E . Early models for the Lorenz number were designed based on this isothermal approach, and this direct approach has been used in several recent probes of the experimental Lorenz number of bismuth antimony telluride . A similar approach was also introduced by Lukas et al for doped bismuth telluride and bismuth–antimony alloys…”

Section: Resultsmentioning

confidence: 99%

“…Early models for the Lorenz number were designed based on this isothermal approach, 66 and this direct approach has been used in several recent probes of the experimental Lorenz number of bismuth antimony telluride. 67 A similar approach was also introduced by Lukas et al for doped bismuth telluride and bismuth−antimony alloys. 68 Here, we find that, at room temperature, a plot of κ total vs σ for the samples in the CaAgSb 1−x Bi x series yields a linear trend (Figure 8c inset), suggesting that the L does not vary strongly at room temperature as a function of either Bi content or crystal structure.…”

Section: Phase Identificationmentioning

confidence: 96%

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Alloying-Induced Structural Transition in the Promising Thermoelectric Compound CaAgSb

Shawon,

Guetari,

Ciesielski

et al. 2024

Chem. Mater.

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AMX Zintl compounds, crystallizing in several closely related layered structures, have recently garnered attention due to their exciting thermoelectric properties. In this study, we show that orthorhombic CaAgSb can be alloyed with hexagonal CaAgBi to achieve a solid solution with a structural transformation at x ∼ 0.8. This transition can be seen as a switch from three-dimensional (3D) to twodimensional (2D) covalent bonding in which the interlayer M−X bond distances expand while the in-plane M−X distances contract. Measurements of the elastic moduli reveal that CaAgSb 1−x Bi x becomes softer with increasing Bi content, with the exception of a steplike 10% stiffening observed at the 3D-to-2D phase transition. Thermoelectric transport measurements reveal promising Hall mobility and a peak zT of 0.47 at 620 K for intrinsic CaAgSb, which is higher than those in previous reports for unmodified CaAgSb. However, alloying with Bi was found to increase the hole concentration beyond the optimal value, effectively lowering the zT. Interestingly, analysis of the thermal conductivity and electrical conductivity suggests that the Bi-rich alloys are low Lorenz-number (L) materials, with estimated values of L well below the nondegenerate limit of L = 1.5 × 10 −8 W Ω K −2 , in spite of the metallic-like transport properties. A low Lorenz number decouples lattice and electronic thermal conductivities, providing greater flexibility for enhancing thermoelectric properties.

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Section: Resultsmentioning

confidence: 99%

Section: Phase Identificationmentioning

confidence: 96%

Alloying-Induced Structural Transition in the Promising Thermoelectric Compound CaAgSb

Shawon,

Guetari,

Ciesielski

et al. 2024

Chem. Mater.

View full text Add to dashboard Cite

show abstract

“…As we know, at temperatures close to 300 K or lower, bipolar effects are likely to be negligible, so the phonon thermal conductivity (κ lat ) can be obtained simply by subtracting the electronic thermal conductivity (κ ele ) from the total thermal conductivity (κ). We employed the Wiedemann−Franz Law to estimate the κ ele , given by κ ele = LσT, where L represents the Lorenz number, which can be determined by considering the scattering parameter and the measured Seebeck coefficient [25]. Due to the nonlinear variation of the sample's R ′ , the error in thermal conductivity above 360 K is significant, highlighting the limitations encountered in this measurement.…”

Section: Thermal Conductivity Measurements Of Filmmentioning

confidence: 99%

Enhancement of ZT in Bi0.5Sb1.5Te3 Thin Film through Lattice Orientation Management

Tsai,

Chen,

Vankayala

et al. 2024

Nanomaterials

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Thermoelectric power can convert heat and electricity directly and reversibly. Low-dimensional thermoelectric materials, particularly thin films, have been considered a breakthrough for separating electronic and thermal transport relationships. In this study, a series of Bi0.5Sb1.5Te3 thin films with thicknesses of 0.125, 0.25, 0.5, and 1 μm have been fabricated by RF sputtering for the study of thickness effects on thermoelectric properties. We demonstrated that microstructure (texture) changes highly correlate with the growth thickness in the films, and equilibrium annealing significantly improves the thermoelectric performance, resulting in a remarkable enhancement in the thermoelectric performance. Consequently, the 0.5 μm thin films achieve an exceptional power factor of 18.1 μWcm−1K−2 at 400 K. Furthermore, we utilize a novel method that involves exfoliating a nanosized film and cutting with a focused ion beam, enabling precise in-plane thermal conductivity measurements through the 3ω method. We obtain the in-plane thermal conductivity as low as 0.3 Wm−1K−1, leading to a maximum ZT of 1.86, nearing room temperature. Our results provide significant insights into advanced thin-film thermoelectric design and fabrication, boosting high-performance systems.

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Experimental estimation of the Lorenz number and scattering parameter for p-type bismuth antimony telluride via multiple doping under constant temperature conditions

Cited by 2 publications

References 55 publications

Alloying-Induced Structural Transition in the Promising Thermoelectric Compound CaAgSb

Alloying-Induced Structural Transition in the Promising Thermoelectric Compound CaAgSb

Enhancement of ZT in Bi0.5Sb1.5Te3 Thin Film through Lattice Orientation Management

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