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

DOI: 10.1016/j.jeurceramsoc.2020.07.021 DOI Help

Authors: D. T. Alvarez-ruiz (University of Manchester) , F. Azough (University of Manchester) , Thomas Slater (Diamond Light Source) , Sarah J. Day (Diamond Light Source) , R. Freer (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Journal Of The European Ceramic Society

State: Published (Approved)
Published: July 2020

Abstract: Ga2O3(ZnO)m (m = integer) homologous compounds are naturally occurring nanostructured materials. Their intrinsically low thermal conductivity makes them attractive for thermoelectric applications. High density Ga2O3(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 to 900 K; compositions with m=15 showed improved power factor of 140 µW/m. K2 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.

Journal Keywords: Thermoelectric; Homologous compounds; Nanostructure; Thermal conductivity

Subject Areas: Materials


Instruments: I11-High Resolution Powder Diffraction