Testing and Modeling of Functionally Graded Aluminum‐Doped Zinc Oxide Using Spark Plasma Sintering and Discrete Powder Layers of Varying Composition. Issue 1 (12th November 2021)

• Record Type: Journal Article
• Authors: Cramer, Corson L.; Wang, Hsin; Lance, Michael J.; Trofimov, Artem A.; Cakmak, Ercan; Jin, Zhi-He
• Is Part Of: Physica status solidi. Volume 219:Issue 1(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2021-11-12
• Subjects: Al-doped ZnO -- functionally graded materials -- thermoelectrics; Solid state physics -- Periodicals; Solids -- Industrial applications -- Periodicals; 530.41
• DOI: 10.1002/pssa.202100483
• Languages: English
• ISSNs: 1862-6300

Abstract

Abstract : Functionally graded material (FGM) ZnO is made via spark plasma sintering/field‐assisted sintering technique (SPS/FAST) by varying the Al dopant content along the z ‐axis or pressing direction. A wide range of Al content (0–5 wt%) is used by adding Al powder to nanosized ZnO powder. Thermoelectric (TE) measurements are done on the FGM and individual layers made separately. X‐ray diffraction (XRD) shows two phases, ZnO and spinel phase (ZnAl2 O4 ). High‐resolution Raman spectroscopy reveals doped ZnO and spinel phase (ZnAl2 O4 ) spatially and shows segregation in the layer with highest Al content. Electron backscatter diffraction (EBSD) reveals noticeable grain growth with decreasing Al content, and there is a common, random preferred orientation in all layers. The tested properties are used to simulate efficiency curves for a discretely graded, five‐layer FGM as well as a homogenous material, where both graded structures provide an opportunity to widen the current density ranges and thus the temperature range of useful energy conversion. Abstract : An aluminum (Al) dopant gradient across a bulk Al‐doped zinc oxide (ZnO) is achievable with powders and spark plasma sintering (SPS). Al helps improve thermoelectric properties and also adds to spinel phase formation. Thermoelectric properties testing and modeling of the efficiency show that the Al content gradation in the thickness of the ZnO increases the thermoelectric performance.