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ABSTRACT We have studied the substitution of antimony by tin and tellurium in n-type skutterudite... more ABSTRACT We have studied the substitution of antimony by tin and tellurium in n-type skutterudites CoSb2.8Snx Te0.2−x . The samples were made by ball milling ingots and hot pressing the ball-milled nanopowder. Rather than filling the cage of the structure, we aimed to use disorder in pnictogen rings by elemental substitution of Sb by Sn and Te. In skutterudite CoSb3, the dominant heat-carrying phonons are associated with the vibrational modes of the Sb-rings; disorder in the rings can be an effective way to suppress the thermal transport. By suitably tuning the contents of Sn and Te in the skutterudites, we have suppressed the thermal conductivity and achieved a power factor of ~42 μW cm−1 K−2 at 530°C. A peak thermoelectric figure of merit (ZT) reaches ~1.1 at 530°C for CoSb2.8Sn0.005Te0.195. This ZT value is comparable with that of some of the single-filled skutterudites.
We present a study on the dimensionless thermoelectric figure-of-merit (ZT) of nanostructured Yb ... more We present a study on the dimensionless thermoelectric figure-of-merit (ZT) of nanostructured Yb x Co 4 Sb 12 (x = 0.2, 0.35, 0.45. 0.5 and 0.6) made by hot pressing the nanopowder obtained from ball milling an ingot in comparison with that made directly from ball milling the elements. It was found that the electrical conductivity of the sample made from the ingot is higher and the thermal conductivity is lower compared to the sample made from directly ball milling the elements. It is believed that the higher electrical conductivity is due to the presence of fewer defects, while the lower thermal conductivity may be due to stronger phonon scattering from the different grain sizes. We have achieved a peak ZT of $1.4 at 550°C in Yb 0.35 Co 4 Sb 12 .
Physical Chemistry Chemical Physics, 2014
We have synthesized Ni compensated Ce and Nd double filled p-type skutterudites CexNdxFe3.7Ni0.3S... more We have synthesized Ni compensated Ce and Nd double filled p-type skutterudites CexNdxFe3.7Ni0.3Sb12 with x = 0.35, 0.40, 0.45, and 0.5 by a melting-quenching-annealing method. The samples were made by directly hot pressing the hand ground powder at 650 °C for 5 minutes at a pressure of about 80 MPa. Since Ni has two more electrons than Fe, a lower power factor and a stronger bipolar effect in thermal conductivity are expected at higher temperature. In the experiments, we have demonstrated that by suitably tuning the Fe-Ni ratio and filler concentration, we can achieve both a higher power factor (∼35 μW cm(-1) K(-2) at 535 °C) and a lower thermal conductivity (∼2.1 W m(-1) K(-1) at room temperature and ∼2.7 W m(-1) K(-1) at 535 °C) in Ce0.4Nd0.4Fe3.7Ni0.3Sb12. A peak thermoelectric figure-of-merit of ∼1.1 at 475 °C is achieved in Ce0.4Nd0.4Fe3.7Ni0.3Sb12.
Microscopy and Microanalysis, 2007
Microscopy and Microanalysis, 2009
Applied Physics A, 2009
A Standard Reference Material (SRM ™ ) for the Seebeck coefficient is critical for inter-laborato... more A Standard Reference Material (SRM ™ ) for the Seebeck coefficient is critical for inter-laboratory data comparison and for instrument calibration. To develop this SRM ™ , we have conducted an international round-robin measurement survey of two candidate materials-undoped Bi 2 Te 3 and constantan (55% Cu and 45% Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of commercial and custom-built measurement systems and techniques. We report the results of these measurements and the statistical analysis performed. Based on this extensive study, we have selected Bi 2 Te 3 as the prototype standard material.
ABSTRACT We have studied the substitution of antimony by tin and tellurium in n-type skutterudite... more ABSTRACT We have studied the substitution of antimony by tin and tellurium in n-type skutterudites CoSb2.8Snx Te0.2−x . The samples were made by ball milling ingots and hot pressing the ball-milled nanopowder. Rather than filling the cage of the structure, we aimed to use disorder in pnictogen rings by elemental substitution of Sb by Sn and Te. In skutterudite CoSb3, the dominant heat-carrying phonons are associated with the vibrational modes of the Sb-rings; disorder in the rings can be an effective way to suppress the thermal transport. By suitably tuning the contents of Sn and Te in the skutterudites, we have suppressed the thermal conductivity and achieved a power factor of ~42 μW cm−1 K−2 at 530°C. A peak thermoelectric figure of merit (ZT) reaches ~1.1 at 530°C for CoSb2.8Sn0.005Te0.195. This ZT value is comparable with that of some of the single-filled skutterudites.
We present a study on the dimensionless thermoelectric figure-of-merit (ZT) of nanostructured Yb ... more We present a study on the dimensionless thermoelectric figure-of-merit (ZT) of nanostructured Yb x Co 4 Sb 12 (x = 0.2, 0.35, 0.45. 0.5 and 0.6) made by hot pressing the nanopowder obtained from ball milling an ingot in comparison with that made directly from ball milling the elements. It was found that the electrical conductivity of the sample made from the ingot is higher and the thermal conductivity is lower compared to the sample made from directly ball milling the elements. It is believed that the higher electrical conductivity is due to the presence of fewer defects, while the lower thermal conductivity may be due to stronger phonon scattering from the different grain sizes. We have achieved a peak ZT of $1.4 at 550°C in Yb 0.35 Co 4 Sb 12 .
Physical Chemistry Chemical Physics, 2014
We have synthesized Ni compensated Ce and Nd double filled p-type skutterudites CexNdxFe3.7Ni0.3S... more We have synthesized Ni compensated Ce and Nd double filled p-type skutterudites CexNdxFe3.7Ni0.3Sb12 with x = 0.35, 0.40, 0.45, and 0.5 by a melting-quenching-annealing method. The samples were made by directly hot pressing the hand ground powder at 650 °C for 5 minutes at a pressure of about 80 MPa. Since Ni has two more electrons than Fe, a lower power factor and a stronger bipolar effect in thermal conductivity are expected at higher temperature. In the experiments, we have demonstrated that by suitably tuning the Fe-Ni ratio and filler concentration, we can achieve both a higher power factor (∼35 μW cm(-1) K(-2) at 535 °C) and a lower thermal conductivity (∼2.1 W m(-1) K(-1) at room temperature and ∼2.7 W m(-1) K(-1) at 535 °C) in Ce0.4Nd0.4Fe3.7Ni0.3Sb12. A peak thermoelectric figure-of-merit of ∼1.1 at 475 °C is achieved in Ce0.4Nd0.4Fe3.7Ni0.3Sb12.
Microscopy and Microanalysis, 2007
Microscopy and Microanalysis, 2009
Applied Physics A, 2009
A Standard Reference Material (SRM ™ ) for the Seebeck coefficient is critical for inter-laborato... more A Standard Reference Material (SRM ™ ) for the Seebeck coefficient is critical for inter-laboratory data comparison and for instrument calibration. To develop this SRM ™ , we have conducted an international round-robin measurement survey of two candidate materials-undoped Bi 2 Te 3 and constantan (55% Cu and 45% Ni alloy). Measurements were performed in two rounds by twelve laboratories involved in active thermoelectric research using a number of commercial and custom-built measurement systems and techniques. We report the results of these measurements and the statistical analysis performed. Based on this extensive study, we have selected Bi 2 Te 3 as the prototype standard material.