Thermal Transport and Thermoelectric Effect in Composites of Alumina and Graphene-Augmented Alumina Nanofibers

Abstract

The remarkable tunability of 2D carbon structures combined with their non-toxicity renders them interesting candidates for thermoelectric applications. Despite some limitations related to their high thermal conductivity and low Seebeck coefficients, several other unique properties of the graphene-like structures could out-weight these weaknesses in some applications. In this study, hybrid structures of alumina ceramics and graphene encapsulated alumina nanofibers are processed by spark plasma sintering to exploit advantages of thermoelectric properties of graphene and high stiffness of alumina. The paper focuses on thermal and electronic transport properties of the systems with varying content of nanofillers (1–25 wt.%) and demonstrates an increase of the Seebeck coefficient and a reduction of the thermal conductivity with an increase in filler content. As a result, the highest thermoelectric figure of merit is achieved in a sample with 25 wt.% of the fillers corresponding to ~3 wt.% of graphene content. The graphene encapsulated nanofibrous fillers, thus, show promising potential for thermoelectric material designs by tuning their properties via carrier density modification and Fermi engineering through doping.

Mixed Electronic-Ionic Conductivity and Stability of Spark Plasma Sintered Graphene-Augmented Alumina Nanofibres Doped Yttria Stabilized Zirconia GAlN/YSZ Composites

“…Since the discovery of single layer graphene (Gr) [ 1 ], the ceramic matrix composites reinforced by Gr have attracted great attention. Over the last ten years, the use of graphene and its derivatives for the design of ceramic composites opened new frontiers for the applications of many existing ceramic matrices (SiC, Si 3 N 4 , ZrO 2 ) as for example, energy conversion and storage, biomaterials and bone engineering, thermoelectric generators ([ 2 , 3 ], additive manufacturing technologies, bioceramics and bone regeneration engineering [ 4 ], aerospace and engineering, etc. [ 5 , 6 , 7 , 8 ].…”

Graphene-Based Materials, Their Composites, and Potential Applications

“…The article by Saffar Shamshirgar [ 15 ] studies the thermoelectric effect of composites containing graphene-coated γ- Al 2 O 3 fibers that were coated by CVD methods, evidencing the notable increase in the thermopower factor for specific compositions and, accordingly, their potential use for waste heat conversion.…”

“… A schematic diagram of the graphene composites spectrum and their potential uses along with representative examples of materials and uses from the articles included in this Special Issue. ( a ) A schematic of the applications of graphene-based composites in Li-ion battery electrodes described in [ 11 ]; ( b ) a high annular dark field (HAADF) micrograph of an Al/2GNP/1Al 2 O 3 composite [ 13 ]; ( c ) an isometric view of a PAO8/ZDDP/graphene W-DLC surface after a ball-on-disc test [ 14 ]; ( d ) CVD graphene-coated γ-Al 2 O 3 nanofiber [ 15 ]; ( e ) reinforced 3D-printed MWCNT and rGO/Al 2 O 3 scaffolds [ 16 ]; ( f ) a schematic of an experimental setup for gas-sensing applications [ 10 ]; ( g ) a schematic diagram of sulfamethoxazole detection by silica-coated GQDs [ 12 ]. …”