Effect of aliovalent substituted highly disordered GeTe compound's thermoelectric performance
Dr. Raman Sankar and his group, in collaboration with Prof. Kuei-Hsien Chen (IAMS, Academia Sinica) and Prof. Anver Aziz (J.M.I. New Delhi, India), explored and optimized the Ge0.9-xSb0.1PxTe (x = 0.01 to 0.05) material's highest thermoelectric performance at elevated temperatures. Intrinsic Ge vacancy control and manipulation of Ge (+2) with Sb/P (+3) increased the charge contribution to power factor improvement to ∼42 µWcm-1K-2 while minimizing the lattice thermal contribution to ∼0.4 W/mK. This resulted in an increase in thermoelectric performance of ∼2.4 @ 773 K for the Ge0.88Sb0.1P0.02Te sample. The inclusion of atomically disordered Sb/P ions considerably increases the scattering effects caused by the point defect, whereas stretched grain boundaries reveal the decreased lattice thermal contribution. The current work demonstrates the effectiveness of phosphorus as a co-dopant in increasing the average thermoelectric performance (ZTavg) value over the GeTe operating temperature range.
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