@article {3849,
	title = {Influence of GeP precipitates on the thermoelectric properties of P-type GeTe and Ge0.9-xPxSb0.1Te compounds},
	journal = {CrystEngComm},
	volume = {20},
	year = {2018},
	note = {n/a},
	month = {2018},
	pages = {6449 - 6457},
	publisher = {The Royal Society of Chemistry},
	abstract = {<p>Germanium telluride (GeTe) is a very well known IV{\textendash}VI group semiconducting material with the advantageous property of showing metallic conduction, which materializes from its superior carrier concentration (n) (high number of Ge vacancies). A systematic investigation into the thermoelectric properties (TEP) of GeTe was reported by way of carrier concentration (n) engineering. The present investigation focuses on studying the effects of doping (antimony {\textendash} Sb) and co-doping (phosphorus {\textendash} P) on the 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, or 0.05) samples via a non-equilibrium solid state melt quenching (MQ) process, followed by hot press consolidation. Temperature dependent synchrotron X-ray diffraction studies reveal a phase transition from rhombohedral to simple cubic in the Ge0.9-xPxSb0.1Te system at 573 K, which is clearly reflected in the TEP. Further high resolution transmission electron microscopy (HRTEM) studies reveal the pseudo-cubic nature of the sample. However, powder X-ray diffraction (PXRD) and field emission scanning electron microscopy (FESEM) images and energy dispersive X-ray spectroscopy (EDX) studies confirm the presence of germanium phosphide (GeP) in all P-doped samples. The presence of a secondary phase and point defects (Sb \&amp; P) enhanced the additional scattering effects in the system, which influenced the Seebeck coefficient and thermal conductivity of GeTe. A significant enhancement in the Seebeck coefficient (S) to \~{}225 μV K-1 and a drastic reduction in thermal conductivity (κ) to \~{}1.2 W mK-1 effectively enhanced the figure-of-merit (ZT) to \~{}1.72 at 773 K for Ge0.87P0.03Sb0.1Te, which is a \~{}3 fold increase for GeTe. Finally, P co-doped Ge0.9Sb0.1Te demonstrates an enhancement in ZT, making it a good candidate material for power generation applications.</p>
},
	url = {http://dx.doi.org/10.1039/C8CE01134F},
	author = {Rajeev Gandhi, J. and Nehru, Raja and Chen, Sheng-Ming and Raman Sankar and Bayikadi, Khasim Saheb and Sureshkumar, Palanivel and Kuei-Hsien Chen and Li-Chyong Chen}
}
