Rapid consolidation of powdered materials by induction hot pressing

LaLonde, Aaron D.; Ikeda, Teruyuki; Snyder, G. Jeffrey

doi:10.1063/1.3534080

Cited by 119 publications

(76 citation statements)

References 9 publications

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“…The obtained powders of Cu 2 ZnGeSe 4Àx S x were hand ground and consolidated into 1-1.5 mm thick, 12 mm diameter disks at 873 K for 5 hours (x ¼ 0), 1073 K for 6 hours (x ¼ 1), and 973 K for 6 hours (x $ 2) under a pressure of 40 MPa by induction hot pressing in high density graphite dies. 19 The resulting samples have more than 95% theoretical density, determined from the mass and geometry of the consolidated disks.…”

Section: Methodsmentioning

confidence: 99%

Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

et al. 2014

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Recently, copper selenides have shown to be promising thermoelectric materials due to their possible superionic character resulting from mobile copper cations. Inspired by this recent development in the class of quaternary copper selenides we have focused on the structure-to-property relationships in the solid solution series Cu 2 ZnGeSe 4Àx S x . The material exhibits an insulator-to-metal transition at higher temperatures, with a transition temperature dependent on the sulfur content. However, the lattice parameters show linear thermal expansion at elevated temperatures only and therefore no indication of a structural phase transformation.63 Cu nuclear magnetic resonance shows clear indications of Cu located on at least two distinct sites, which eventually merge into one (apparent) site above the phase transformation. In this manuscript the temperature dependent lattice parameters and electronic properties of the solid solution Cu 2 ZnGeSe 4Àx S x are reported in combination with 63 Cu NMR, and an attempt will be made to relate the nature of the electronic phase transformation to a superionic phase transformation and a changing covalent character of the lattice upon anion substitution in this class of materials.

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Section: Methodsmentioning

confidence: 99%

Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

et al. 2014

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“…Polycrystalline Ge 1 − x Bi x Te (x ⩽ 0.1) and Ge 1+δ Te (−0.04 ⩽ δo0.06) samples with controlled carrier concentrations were synthesized by melting stoichiometric amounts of high-purity elements (499.99%) in vacuum quartz ampoules at 1073 K for 6 h, quenching in cold water and annealing at 873 K for 3 days. The ingots were hand ground into fine powders for X-ray diffraction, and for hot-pressing by induction heating 67 at 853 K for 40 min under a uniaxial pressure of ∼ 80 MPa. The obtained dense pellets (498% of the theoretical density) were ∼ 12 mm in diameter and 1.5 mm in thickness for the transport property measurements.…”

Section: Methodsmentioning

confidence: 99%

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

et al. 2017

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PbTe and SnTe in their p-type forms have long been considered high-performance thermoelectrics, and both of them largely rely on two valence bands (the first band at L point and the second one along the Σ line) participating in the transport properties. This work focuses on the thermoelectric transport properties inherent to p-type GeTe, a member of the group IV monotellurides that is relatively less studied. Approximately 50 GeTe samples have been synthesized with different carrier concentrations spanning from 1 to 20 × 10 20 cm − 3 , enabling an insightful understanding of the electronic transport and a full carrier concentration optimization for the thermoelectric performance. When all of these three monotellurides (PbTe, SnTe and GeTe) are fully optimized in their p-type forms, GeTe shows the highest thermoelectric figure of merit (zT up to 1.8). This is due to its superior electronic performance, originating from the highly degenerated Σ band at the band edge in the low-temperature rhombohedral phase and the smallest effective masses for both the L and Σ bands in the high-temperature cubic phase. The high thermoelectric performance of GeTe that is induced by its unique electronic structure not only provides a reference substance for understanding existing research on GeTe but also opens new possibilities for the further improvement of the thermoelectric performance of this material.

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“…The annealed material was hand ground and consolidated into 1-1.5 mm thick, 12 mm diameter disks at 873 K for 5 hours under a pressure of 40 MPa by induction hot pressing in high density graphite dies. 29 The resulting samples have more than 95% theoretical density, determined from the mass and geometry of the consolidated disks.…”

Section: 28mentioning

confidence: 99%

Band convergence in the non-cubic chalcopyrite compounds Cu₂MGeSe₄

et al. 2014

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aInspired by recent theoretical predictions on band convergence in the tetragonal chalcopyrite compounds, we have explored the influence of the crystal structure on the transport and bandstructure of different quaternary chalcopyrites. In theory, a changing lattice parameter ratio of c/2a towards unity should lead to band convergence due to a more cubic and higher symmetry structure. In accordance with this prediction, the different solid solutions explored in this manuscript show a significant impact on the electronic transport depending on the ratio of the lattice parameters. An increasing lattice parameter ratio results in an increase of the carrier effective masses which can be explained by converging bands, ultimately leading to an increase of the power factor and thermoelectric figure of merit in the class of non-cubic chalcopyrite compounds Cu 2 MGeSe 4 . However, the calculations via density functional theory show that the critical value of c/2a, where band convergence occurs, will be different from unity due to symmetry and chemical influences on the band structure.

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Rapid consolidation of powdered materials by induction hot pressing

Cited by 119 publications

References 9 publications

Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

Band convergence in the non-cubic chalcopyrite compounds Cu₂MGeSe₄

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Rapid consolidation of powdered materials by induction hot pressing

Cited by 119 publications

References 9 publications

Bond strength dependent superionic phase transformation in the solid solution series Cu2ZnGeSe4−xSx

Bond strength dependent superionic phase transformation in the solid solution series Cu2ZnGeSe4−xSx

Electronic origin of the high thermoelectric performance of GeTe among the p-type group IV monotellurides

Band convergence in the non-cubic chalcopyrite compounds Cu2MGeSe4

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Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

Bond strength dependent superionic phase transformation in the solid solution series Cu₂ZnGeSe_4−xS_x

Band convergence in the non-cubic chalcopyrite compounds Cu₂MGeSe₄