Enhanced Seebeck coefficient by energy filtering in Bi-Sb-Te based composites with dispersed Y2O3 nanoparticles

Madavali, Babu; Kim, Hyo-Seob; Lee, Kap Ho; Hong, Soon‐Jik

doi:10.1016/j.intermet.2016.11.002

Cited by 73 publications

(71 citation statements)

References 33 publications

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“…It is observed that the grain size of 20‐minute BiSbTe/ZnO (2 wt%) composite bulk can be estimated as ~1 μm, which is fairly small grains as compared with the host matrix. These reductions in grain sizes at 20 minutes are consistence with our previous studies . The dispersion of ZnO is identified with SEM‐EDS mapping for 5 and 20 minutes, respectively (Figure E and F).…”

Section: Resultsmentioning

confidence: 99%

“…It is evident that the BiSbTe matrix shows high relative density, while its value is slightly decreased with addition of ZnO nanorods. The dispersion of ZnO nanorods may exhibit back stress force during the sintering, which might result slight decrease in relative density . The micro‐Vickers hardness of BiSbTe matrix was measured as 68 HV, and increased upon the dispersion of ZnO with different milling times.…”

Section: Resultsmentioning

confidence: 99%

“…The micro‐Vickers hardness of BiSbTe matrix was measured as 68 HV, and increased upon the dispersion of ZnO with different milling times. The increase in hardness is primarily due to the reduction in grain size (from micron order to submicron order) and dispersion strengthening mechanism . The improved hardness values of the composites favor special qualities such as easy handling, as well as reduced waste in cutting and other machining operations during module preparation.…”

Section: Resultsmentioning

confidence: 99%

“…For ambient room temperature (RT) applications, bismuth telluride (Bi 2 Te 3 )‐based alloys are much attracted due to their high‐energy conversion thermoelectric efficient at RT . So far, many researchers have studied TE properties and reported improved ZT values by forming composite structures and dispersion of nanoinclusions in bulk matrix thereby controlling the Seebeck coefficient and/or electrical conductivity via introduction of energy filtering effect that can filter the low energy electrons and allows only high energy (hot) electrons . In addition, thermal conductivity is also reduced by phonon scattering at grain boundaries and/or interfaces between nanoinclusion and matrix.…”

Section: Introductionmentioning

confidence: 99%

“…3 So far, many researchers have studied TE properties and reported improved ZT values by forming composite structures and dispersion of nanoinclusions in bulk matrix thereby controlling the Seebeck coefficient and/or electrical conductivity via introduction of energy filtering effect that can filter the low energy electrons and allows only high energy (hot) electrons. 4,5 In addition, thermal conductivity is also reduced by phonon scattering at grain boundaries and/or interfaces between nanoinclusion and matrix. Hsu et al 6 reported enhanced TE properties in the AgPb m SbTe m+2 system with nanoscale inhomogeneous of Ag and Sb embedded in PbTe matrix that can dramatically decrease the thermal conductivity by increasing phonon scattering without affecting the electrical properties.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Investigation of microstructure and thermoelectric properties of p‐type BiSbTe/ZnO composites

Madavali

Lee

Kim

et al. 2017

Int J Applied Ceramic Tech

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In this research work, p-type BiSbTe/ZnO (2 wt%) nanocomposite powders were fabricated by high-energy ball milling at different milling times, and subsequently, powders were consolidated by spark plasma sintering at 673 K temperature. The existence of nanoinclusions was confirmed by SEM-EDS mapping. Vickers hardness values greatly improved due to reduction in grain size which prevents the crack propagation and dispersion strengthening mechanism. The decrease in carrier density, which plays a critical role in thermoelectrics, dramatically increases the Seebeck coefficient, and subsequently, decreases the electrical conductivity upon the dispersion of ZnO nanorods into the BiSbTe matrix. The thermal conductivity was noticeably reduced by~13% in BiSbTe/ZnO composites for 5-minute samples due to blocking of carriers/phonons at interfaces, and/or grain boundaries. The peak ZT of 0.92 was obtained for BiSbTe matrix, and 0.91 for BiSbTe/ZnO (5 minutes) composites at room temperatures. K E Y W O R D Sball milling, Bi 2 Te 3 alloys, nanocomposites, spark plasma sintering, thermoelectric materials 1 | INTRODUCTION Thermoelectric (TE) materials have been crucially used in renewable energy conversion technologies to overcome the energy crisis in the present world. The efficiency of TE materials can be defined by the dimensionless figure of merit, ZT = (a 2 r/K) T, where a, r, K, and T are the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature, respectively. 1 In general, the temperature gradient develops an electrostatic potential, which is defined as the Seebeck coefficient (a = DV/DT for small DT). The Seebeck coefficient gradually decreases with carrier density, while the electrical conductivity increases. The thermal conductivity is proportional to the carrier density, which is contributed by both electrons and phonons. The ZT should be high, and at least unity (ZT ≥ 1) to maintain the device efficiency over 10%. 2,3 For ambient room temperature (RT) applications, bismuth telluride (Bi 2 Te 3 )-based alloys are much attracted due to their high-energy conversion thermoelectric efficient at RT. 3 So far, many researchers have studied TE properties and reported improved ZT values by forming composite structures and dispersion of nanoinclusions in bulk matrix thereby controlling the Seebeck coefficient and/or electrical conductivity via introduction of energy filtering effect that can filter the low energy electrons and allows only high energy (hot) electrons. 4,5 In addition, thermal conductivity is also reduced by phonon scattering at grain boundaries and/or interfaces between nanoinclusion and matrix. Hsu et al 6 reported enhanced TE properties in the AgPb m SbTe m+2 system with nanoscale inhomogeneous of Ag and Sb embedded in PbTe matrix that can dramatically decrease the thermal conductivity by increasing phonon scattering without affecting the electrical properties. Li et al 7 reported BiSbTe-based nanocomposites with high ZT values through dispersion of SiC nanopartic...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Investigation of microstructure and thermoelectric properties of p‐type BiSbTe/ZnO composites

Madavali

Lee

Kim

et al. 2017

Int J Applied Ceramic Tech

Self Cite

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Energy Filtering of Charge Carriers: Current Trends, Challenges, and Prospects for Thermoelectric Materials

Gayner

Amouyal

2019

Adv Funct Materials

329

231

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Exhaustive attempts are made in recent decades to improve the performance of thermoelectric materials that are utilized for waste heat-to-electricity conversion. Energy filtering of charge carriers is directed toward enhancing the material thermopower. This paper focuses on the theoretical concepts, experimental evidence, and the authors' view of energy filtering in the context of thermoelectric materials. Recent studies suggest that not all materials experience this effect with the same intensity. Although this effect theoretically demonstrates improvement of the thermopower, applying it poses certain constraints, which demands further research. Predicated on data documented in literature, the unusual dependence of the thermopower and conductivity upon charge carrier concentrations can be altered through the energy filtering approach. Upon surmounting the physical constraints discussed in this article, thermoelectric materials research may gain a new direction to enhance the power factor and thermoelectric figure of merit.

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High Performance BiSbTe Alloy for Superior Thermoelectric Cooling

Sun

Dong

et al. 2023

Adv Funct Materials

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At present, the weak thermoelectric and mechanical performance of zone‐melting bismuth telluride alloys cannot support the further improvement of cooling and processing performance of semiconductor refrigeration devices. Here, MnO2 is added into high‐strength Bi0.4Sb1.6Te3 prepared by ball milling method to optimize its thermoelectric transport properties. Via in situ reaction, Sb2O3 nano‐precipitates are formed in the matrix, which also leads to the surplus of Te element. As results, the donor‐like effect is suppressed, thereby increasing carrier concentration and power factor. Besides, volatilization of Te‐rich phases during sintering leaves plentiful nanopores, which together with Sb2O3 nano‐precipitates significantly decrease the lattice thermal conductivity. Eventually, the maximum ZT reaches 1.43 at 75 °C for the Bi0.4Sb1.6Te3+0.01MnO2 sample. On this basis, a 31‐pairs module made of the material and commercial n‐type BiTeSe produces large temperature differences (ΔT) of 70.1, 80.8, and 89.4 K at the hot‐side temperature (Th) of 300, 325, and 350 K respectively, which are highly competitive. The maximum coefficient of performance of 8.6 and cooling capacity of 7 W are achieved when Th is set as 325 K. This excellent progress will promote the further development of bismuth telluride refrigeration modules.

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Enhanced Seebeck coefficient by energy filtering in Bi-Sb-Te based composites with dispersed Y2O3 nanoparticles

Cited by 73 publications

References 33 publications

Investigation of microstructure and thermoelectric properties of p‐type BiSbTe/ZnO composites

Investigation of microstructure and thermoelectric properties of p‐type BiSbTe/ZnO composites

Energy Filtering of Charge Carriers: Current Trends, Challenges, and Prospects for Thermoelectric Materials

High Performance BiSbTe Alloy for Superior Thermoelectric Cooling

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