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“Influence of GeP precipitates on the thermoelectric properties of the doped P-type Ge0.9-xPxSb0.1Te compound”

Abstract

Germanium Telluride (GeTe) is a very well known IV-VI group semiconducting material with advantageous property of metallic conduction; materialized from its superior carrier concentration (n) (high Ge vacancies). A systematic investigation on thermoelectric properties (TEP) of GeTe was reported by all the way through carrier concentration (n) engineering. The present investigation focused to study the effect of doping (Antimony- Sb) and co-doping (Phosphor- P) on TEP of GeTe. In order to understand the system we have prepared p-type GeTe and Ge0.9-xPxSb0.1Te (x= 0, 0.01, 0.03, 0.05) samples by non-equilibrium solid state melt quenching (MQ) process proceeding with hot press consolidation. Temperature dependent synchrotron X-ray diffraction reveals the phase transition from rhombohedral to simple cubic in Ge0.9-xPxSb0.1Te system at 573 K; which clearly reflects in TEP. Further High Resolution Transmission Electron microscopy (HRTEM) study reveals pseudo cubic nature of the sample. However Powder X-Ray Diffraction (PXRD) and Field Emission Scanning Electron Microscope (FESEM) images with Energy Dispersive X-ray spectrum (EDX) study confirms the Germanium Phosphide (GeP) presence in all P-doped samples. The presence of secondary phase and point defects (Sb & P) enhanced the additional scattering effects in the system, which influenced the Seebeck and thermal conductivity of GeTe. Significant enhancement in Seebeck coefficient (S) ~ 225 μV/K and drastic reduction in thermal conductivity (κ) ~ 1.2 W/mK effectively enhanced the figure-of-merit (ZT) ~ 1.72 at 773K for Ge0.87P0.03Sb0.1Te which is ~ 3 fold increment in GeTe. Finally, P co-doped Ge0.9Sb0.1Te demonstrates enhancement in ZT makes them good candidate materials for power generation application.

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Publication details

The article was received on 11 Jul 2018, accepted on 12 Sep 2018 and first published on 12 Sep 2018


Article type: Paper
DOI: 10.1039/C8CE01134F
Citation: CrystEngComm, 2018, Accepted Manuscript
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    “Influence of GeP precipitates on the thermoelectric properties of the doped P-type Ge0.9-xPxSb0.1Te compound”

    R. G. J, N. Raja, S. M. Chen, R. Sankar, B. Khasimsaheb, P. sureshkumar, K. H. Chen and L. Chen, CrystEngComm, 2018, Accepted Manuscript , DOI: 10.1039/C8CE01134F

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