The effect of nano-twins on the thermoelectric properties of Ga2O3(ZnO)(m) (m=9, 11, 13 and 15) homologous compounds

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Ga 2O 3(ZnO) m (m = integer) homologous compounds are naturally occurring nanostructured materials. Their intrinsically low thermal conductivity makes them attractive for thermoelectric applications. High density Ga 2O 3(ZnO) m (m = 9, 11, 13, and 15) single phase ceramics were prepared by solid-state reaction. Nano-sized, twin-like V-shaped boundaries parallel to b-axis (apex angle ∼ 60°) were observed for all compositions. Atomic resolution Z-contrast imaging and EDS analysis for m = 15 showed segregation of Ga ions at the interface of V-shaped twin boundaries. Thermal and charge transport properties depend on the value of m. Compositions with m = 9 exhibited very low lattice thermal conductivity of 2 to 1.5 W/m.K at 300 K–900 K; compositions with m=15 showed improved power factor of 140 μW/m. K 2 at 900 K leading to a thermoelectric figure of merit (ZT value) of 0.055. This study explores the structural variants and routes to improve the thermoelectric properties of these materials

Bibliographical metadata

Original languageEnglish
Pages (from-to)5549-5558
Number of pages10
JournalJournal of the European Ceramic Society
Issue number15
Publication statusPublished - 1 Dec 2020