High-temperature charge transport and thermoelectric properties of a degenerately Al-doped ZnO nanocomposite

Abstract

2 mol% Al-doped ZnO nanoparticles were consolidated into a ZnO nanocomposite with ZnAl 2 O 4 nanoprecipitates by spark plasma sintering and its high-temperature charge transport and thermoelectric properties were investigated up to 1073 K. The carrier concentration in the nanocomposite was not dependent on the temperature, while the Hall mobility showed positive temperature-dependence due to grain boundary scattering. The negative Seebeck coefficient of the nanocomposite was linearly proportional to the temperature, and the density of the state effective mass (m d *) was evaluated to be 0.33m e by using the Pisarenko relation. Drastic reduction of thermal conductivity (k < 2 W m À1 K À1 ) was achieved in the nanocomposite, and the maximum ZT of 0.34 was obtained at 1073 K.

Enhanced Charge Transport in ZnO Nanocomposite Through Interface Control Using Multiwall Carbon Nanotubes

“…(b), and the inset shows the Fast Fourier Transformation (FFT) diffractogram of the AZO lattice along the zone axis. The average size of the AZO grains and the relative density in the AZO‐MWCNT nanocomposite were approximately 200 nm and 94%, respectively, and these values were almost identical to those for the AZO nanocomposite prepared by sintering of AZO nanoparticles without MWCNTs in our previous study the AZO‐RGO nanocomposite exhibited almost the same average grain size and similar relative density (~94%).…”

“…As reported in our previous work, AZO nanoparticles were synthesized by the solution method using hexamethylenetetramine [(CH 2 ) 6 N 4 , Sigma Aldrich, St. Louis, MO], zinc nitrate hexahydrate [Zn(NO 3 ) 2 ·6H 2 O, Sigma Aldrich], aluminum nitrate nonahydrate [Al(NO 3 ) 3 ·9H 2 O, Sigma Aldrich], and deionized water . The AZO‐MWCNT nanocomposite was prepared using commercially available MWCNTs (carbon >95%, Aldrich) and the synthesized AZO nanoparticles.…”

Thermoelectric transport properties of boron-doped nanocrystalline diamond foils

“…5(a)), a behavior that is not typical for metal-like transport. A similar behavior can be found, e.g., in highly doped nanograined ZnO [56], where it is explained with grain boundary scattering [57,58]. The microstructure influences the electrical conductivity much more than the Seebeck coefficient [56,59].…”

“…The microstructure influences the electrical conductivity much more than the Seebeck coefficient [56,59]. Nam et al measured a linear dependence of the Seebeck coefficient on the temperature and a temperature independent charge carrier concentration despite a strong thermal activation of the electrical conductivity, assigning the activation to an increase in mobility when the grain boundary barrier height surpasses the difference between the Fermi level and the bottom of the conduction band [56].…”

A review of thermoelectric ZnO nanostructured ceramics for energy recovery

“…Among the thermoelectric materials, zinc oxide displays a good seebeck coefficient value, a high thermal stable temperature ranges and low environmental impact [22,23]. The different investigations on ZnO materials present that their thermoelectric properties can be improved by substitution with different element such as Aluminum [1][2][3][4][24][25][26][27][28], Cerium and Dysprosium [29], Gallium [6,[30][31][32], Indium [33], praseodymium [34], Antimony [20] and Nickel [7,19]. Therefore, ZnO as thermoelectric materials is slowly developing, but surely gaining attention as one of the candidates for thermoelectric applications.…”