title: Al-doped zinc oxide nanocomposites with enhanced thermoelectric properties.
abstract: ZnO is a promising high figure-of-merit (ZT) thermoelectric material for power harvesting from heat due to its high melting point, high electrical conductivity σ, and Seebeck coefficient α, but its practical use is limited by a high lattice thermal conductivity κ(L). Here, we report Al-containing ZnO nanocomposites with up to a factor of 20 lower κ(L) than non-nanostructured ZnO, while retaining bulklike α and σ. We show that enhanced phonon scattering promoted by Al-induced grain refinement and ZnAl(2)O(4) nanoprecipitates presages ultralow κ ∼ 2 Wm( -1) K(-1) at 1000 K. The high α∼ -300 μV K(-1) and high σ ∼ 1-10(4) Ω(-1 )m(-1) result from an offsetting of the nanostructuring-induced mobility decrease by high, and nondegenerate, carrier concentrations obtained via excitation from shallow Al donor states. The resultant ZT ∼ 0.44 at 1000 K is 50% higher than that for the best non-nanostructured counterpart material at the same temperature and holds promise for engineering advanced oxide-based high-ZT thermoelectrics for applications.
authors.affiliation: Materials Science and Engineering Department, , Rensselaer Polytechnic Institute , 110 Eighth Street, Troy, New York 12180, United States.
authors.forename: Priyanka
authors.initials: P
authors.lastname: Jood
authors.forename: Rutvik J
authors.initials: RJ
authors.lastname: Mehta
authors.forename: Yanliang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Germanas
authors.initials: G
authors.lastname: Peleckis
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wang
authors.forename: Richard W
authors.initials: RW
authors.lastname: Siegel
authors.forename: Theo
authors.initials: T
authors.lastname: Borca-Tasciuc
authors.forename: Shi Xue
authors.initials: SX
authors.lastname: Dou
authors.forename: Ganpati
authors.initials: G
authors.lastname: Ramanath