Phase decomposition of Ni5Pb2Te3 in diffusion bonded PbTe-Ni interfaces – A TEM and thermodynamic study

Kumar, D and Singh, MP and Ravishankar, N and Chattopadhyay, K (2022) Phase decomposition of Ni5Pb2Te3 in diffusion bonded PbTe-Ni interfaces – A TEM and thermodynamic study. In: Acta Materialia, 241 .

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Abstract

The study of metallurgical phase transformations is essential for developing reliable interconnects in thermoelectric devices. PbTe-based devices are used in mid-temperature range applications, with Ni being the most preferred contact metal. Several studies have reported the direct joining of PbTe and Ni through rapid hot-pressing routes. However, the study of equilibrium phase transformations in these processes is complex owing to many external variables (applied pressure, electrical current, and simultaneous sintering of PbTe). Furthermore, the long-term phase transformation behavior of Ni5Pb2Te3 and (Ni3±xTe2) β2 phases generated from PbTe/Ni interaction has not been examined. This paper reports the phase decomposition of the high-temperature Ni5Pb2Te3 phase in diffusion bonded PbTe/Ni heterointerfaces and presents a general thermodynamic framework to predict such transformations. The phase decomposition is studied through advanced analytical TEM/STEM techniques. The Ni5Pb2Te3 phase transforms into monoclinic β2 and PbTe phases with a lamellae-like arrangement accompanied by the formation of extrinsic stacking faults in the β2 lamellae. Our work highlights an effective experimental technique (solid-state diffusion bonding) that can be applied to study a metal-contact problem in thermoelectrics and outlines a framework to derive essential thermodynamic data in the absence of any experimental measurements and crystallographic information.

Item Type:	Journal Article
Publication:	Acta Materialia
Publisher:	Acta Materialia Inc
Additional Information:	The copyright for this article belongs to Acta Materialia Inc.
Keywords:	Hot pressing; IV-VI semiconductors; Lead alloys; Lead compounds; Nickel; Phase transitions; Sintering; Stacking faults, Formation enthalphy; HRSTEM; Metallurgical phasis; Miedema's theory; Phase decompositions; Phases transformation; Stacking fault ni3te2; Thermodynamic studies; Thermoelectric; Thermoelectric contact, Ternary alloys
Department/Centre:	Division of Chemical Sciences > Materials Research Centre Division of Interdisciplinary Sciences > Interdisciplinary Centre for Energy Research Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited:	19 Oct 2022 09:26
Last Modified:	19 Oct 2022 09:26
URI:	https://eprints.iisc.ac.in/id/eprint/77426

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