Bonding of Lead Telluride to Pure Iron Electrodes

Weinstein, Martin; Mlavsky, A. I.

doi:10.1063/1.1717707

Cited by 34 publications

(30 citation statements)

References 1 publication

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“…Nevertheless, Ni (CTE = 13.4 × 10 − 6 /K) and Fe (CTE = 11.8 × 10 −6 /K) were studied as electrode materials for PbTe [11,19]. The Fe/PbTe joint was found to be successful for n-type material, revealed as a mechanically stable joint with a low electrical resistance at the junction [19]. Temperatures as high as 1073 K were employed to form the Fe/PbTe joint [20], however, which might damage the PbTe.…”

Section: Introductionmentioning

confidence: 99%

One-step bonding of Ni electrode to n-type PbTe — A step towards fabrication of thermoelectric generators

et al. 2016

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PbTe-based thermoelectric materials are good candidates for harvesting waste heat at mid-range temperatures due to their high thermoelectric efficiencies. Excellent quality and reliability of the bonding between the thermoelectric material and the electrode at high temperatures are essential for manufacturing thermoelectric generators. Here, a technique has been developed to achieve high-quality bonding between PbTe and the electrode. We have successfully performed one-step sintering of nickel electrode to n-type PbTe powder using spark plasma sintering. The fabricated interphase, composed of nickel telluride, is continuous and homogeneous across the junction, without visible flaws on the electrode or in the interphase and PbTe. To evaluate the long-term thermal stability of the fabricated bond, an aging test was conducted at 823 K for 360 h under vacuum. The microstructures and chemical composition of the fabricated bonding and the aged sample were investigated in detail by scanning electron microscopy equipped with energy dispersive X-ray spectroscopy analysis. No excess reaction was observed between the electrode and the thermoelectric material after aging, supporting the formation of a chemically stable interphase, which acts as a diffusion barrier. Degradation of the PbTe was detected after aging, however. The fabricated interface meets the required criteria for maximum efficiency of PbTe materials.

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Section: Introductionmentioning

confidence: 99%

One-step bonding of Ni electrode to n-type PbTe — A step towards fabrication of thermoelectric generators

et al. 2016

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“…According to a previous study conducted by NASA, Fe and Ni do not degrade the TE properties of n-type PbTe. 12 However, there are three issues when using Fe as a direct contact material for PbTe: (a) direct bonding of Fe to PbTe is poor because there is only limited diffusion and no reaction between Fe and PbTe, 13 (b) the CTE mismatch of the joints is somewhat high since the CTE of PbTe is about 20 9 10 À6 /K, 14 and (c) the bonding temperature of the joints is above 800°C, which is much higher than the optimal sintering temperature (600°C) of PbTe powders; this may affect the properties of PbTe-based TE materials because of the temperature dependence of the dopant and alloy solubility in PbTe. 15 Compared with Fe, Ni is easier to bond to PbTe.…”

Section: Introductionmentioning

confidence: 99%

Interfacial Reaction Between Nb Foil and n-Type PbTe Thermoelectric Materials During Thermoelectric Contact Fabrication

Xia

Chen

Drymiotis

et al. 2014

Journal of Elec Materi

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PbTe is a high-conversion-efficiency thermoelectric (TE) material that is commonly used in space exploration applications. Integration of PbTe in TE devices has a significant impact on the conversion efficiency and reliability of TE devices. Hence, our effort focuses on developing novel approaches for bonding metallic contacts to PbTe to improve device performance and reliability. In this study, pure Nb foil was directly bonded to PbTe-based TE materials to fabricate the hot-side contacts of TE elements using a rapid hotpress. The materials were sintered at 700°C under pressure of 40 MPa for various holding times. We found that a reaction layer of needle-like Nb 3 Te 4 mixed with Pb forms at the interface of the Nb/PbTe joints and that Pb is distributed in the gaps of the Nb 3 Te 4 grains. We analyze the resulting microstructure and finally calculate the time exponent of the growth kinetics of the Nb 3 Te 4 layer. Fracture surface analysis showed that the Nb/PbTe joint fractures at the interface between Nb and Nb 3 Te 4 and within the PbTe matrix, indicating that the bonding between Nb and Nb 3 Te 4 is weak.

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“…It is also difficult to obtain a metallurgical high-strength joint with Fe and Mo foils. 16,17 These issues are not limited to PbTe but are present in other TE materials as well, such as CoSb 3 -based materials. 18,19 Severe diffusion and the brittleness of the chemical reaction products will undoubtedly lead to degradation of thermoelectric performance, which causes reliability problems during high-temperature operation.…”

Section: Introductionmentioning

confidence: 99%

Interfacial reactions between PbTe-based thermoelectric materials and Cu and Ag bonding materials

Drymiotis

Liao

et al. 2015

J. Mater. Chem. C

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The development of reliable bonding materials for PbTe-based thermoelectric modules that can undergo long-term operations at high temperature is carried out. Two cost-effective materials, Cu and Ag, are isothermally hot-pressed to PbTe-based thermoelectric materials at 550 1C for 3 h under a pressure of 40 MPa by the rapid hot-pressing method. Scanning electron microscopy, electron probe micro-analysis, and X-ray diffraction analysis are employed to identify intermetallic compounds, chemical reactions, and microstructure evolution after the initial assembly and subsequent isothermal aging at 400 1C and 550 1C. We find that Cu diffuses faster than Ag in PbTe. Neither Cu nor Ag is a good bonding material because they both react vigorously with Pb 0.6 Sn 0.4 Te. In order to be able to use Cu electrodes, it would be necessary to insert a diffusion barrier to prevent Cu diffusion into PbTe.

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Bonding of Lead Telluride to Pure Iron Electrodes

Cited by 34 publications

References 1 publication

One-step bonding of Ni electrode to n-type PbTe — A step towards fabrication of thermoelectric generators

One-step bonding of Ni electrode to n-type PbTe — A step towards fabrication of thermoelectric generators

Interfacial Reaction Between Nb Foil and n-Type PbTe Thermoelectric Materials During Thermoelectric Contact Fabrication

Interfacial reactions between PbTe-based thermoelectric materials and Cu and Ag bonding materials

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