TY - JOUR
T1 - Characterization of ZnO thermoelectric ceramics and their microstructures consolidated by two-step spark plasma sintering
AU - Jeong, Ahrong
AU - Ohtaki, Michitaka
AU - Jang, Byungkoog
N1 - Funding Information:
Acknowledgments This work was supported by JSPS KAKENHI Grant Number JP19H02800. The authors would like to thank Associate Prof. K. Suekuni for his technical support during the experiments.
Publisher Copyright:
©2022 The Ceramic Society of Japan. All rights reserved.
PY - 2022/11/1
Y1 - 2022/11/1
N2 - Zinc oxide (ZnO) thermoelectric ceramics were consolidated by spark plasma sintering (SPS) along with one-step/two-step sintering (OS/TS) temperature profiles, the latter employing a strategy of heating to a higher temperature (T1) followed by prolonged sintering at a lower temperature (T2) for densification while preventing grain growth. In the first step, the temperatures and holding times were 1100 and 1150 °C for 15 and 5 min, respectively, and the second-step was maintained at 1050 °C for 30, 60, and 120 min. By combining TS and SPS processes (TS-SPS), high relative densities of 91.494.9 % were achieved without significant grain growth. Electron backscatter diffraction (EBSD) revealed a noticeable grain-growth suppression of 56 % for the TS-SPS sample with T1 = 1100 °C. The highest power factor of 7.8 × 1015 W K12 m11 was achieved for the TS-SPS ZnO, while the lowest thermal conductivity of 4.7 W K11 m11 was achieved for the OS-SPS ZnO, attaining a figure of merit (ZT) of 0.017 at 775 °C.
AB - Zinc oxide (ZnO) thermoelectric ceramics were consolidated by spark plasma sintering (SPS) along with one-step/two-step sintering (OS/TS) temperature profiles, the latter employing a strategy of heating to a higher temperature (T1) followed by prolonged sintering at a lower temperature (T2) for densification while preventing grain growth. In the first step, the temperatures and holding times were 1100 and 1150 °C for 15 and 5 min, respectively, and the second-step was maintained at 1050 °C for 30, 60, and 120 min. By combining TS and SPS processes (TS-SPS), high relative densities of 91.494.9 % were achieved without significant grain growth. Electron backscatter diffraction (EBSD) revealed a noticeable grain-growth suppression of 56 % for the TS-SPS sample with T1 = 1100 °C. The highest power factor of 7.8 × 1015 W K12 m11 was achieved for the TS-SPS ZnO, while the lowest thermal conductivity of 4.7 W K11 m11 was achieved for the OS-SPS ZnO, attaining a figure of merit (ZT) of 0.017 at 775 °C.
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U2 - 10.2109/jcersj2.22097
DO - 10.2109/jcersj2.22097
M3 - Article
AN - SCOPUS:85142352435
SN - 1882-0743
VL - 130
SP - 889
EP - 894
JO - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
JF - Nippon Seramikkusu Kyokai Gakujutsu Ronbunshi/Journal of the Ceramic Society of Japan
IS - 11
ER -