TY - JOUR
T1 - High-entropy MTiO3 perovskite oxides with glass-like thermal conductivity for thermoelectric applications
AU - Zhang, Ping
AU - Lou, Zhihao
AU - Gong, Lingyun
AU - Xu, Jie
AU - Chen, Qian
AU - Reece, Michael John
AU - Yan, Haixue
AU - Dashevsky, Zinovi
AU - Gao, Feng
N1 - Funding Information:
This work was supported by National Natural Science Foundation of China (Nos. 52272123 , 52072301 ), the China-Poland International Collaboration Fund of National Natural Science Foundation of China (No. 51961135301 ), the International Cooperation Foundation of Shaanxi Province ( 2022KW-34 ), the Fundamental Research Funds for the Central Universities (No. D5000210722 ), the Research Fund of State Key Laboratory of Solidification Processing (NPU) (No. 2021-TS-08), the Open Fund of State Key Laboratory of New Ceramic and Fine Processing Tsinghua University (No. KFZD202102 ), and the ‘111 Project’ (No. B20028 ). We would like to thank the Analytical & Testing Center of Northwestern Polytechnical University for the measurements of XRD, BSE- EDS, XPS, TEM and valuable discussion.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2023/3/15
Y1 - 2023/3/15
N2 - High-entropy oxides with complex compositions can be designed to lower the thermal conductivity of SrTiO3-based thermoelectric materials to optimize their properties. High-entropy (Sr0.25Ca0.25Ba0.25RE0.25)TiO3 (RE=Nd, Sm, Eu, Gd, Dy, Ho) ceramics were designed to systematically investigate the effects of critical average ionic radius (rA̅), atomic size disorder factor (δAr), and the mass difference factor (δAm) of A-site elements on the single-phase formation, disorder microstructure, and the thermoelectric properties. The successful synthesis of single-phase perovskite-type ceramics of (Sr0.25Ca0.25Ba0.25Nd0.25)TiO3, (Sr0.25Ca0.25Ba0.25Sm0.25)TiO3, and (Sr0.25 Ca0.25Ba0.25Eu0.25)TiO3 by a solid-state reaction method were reported. When rA̅ <1.377 Å, indicator of δAr≥ 12.86, and δAm≥ 18.6, the pyrochlore phase of Gd2Ti2O7, Dy2Ti2O7, and Ho2Ti2O7 precipitated. Importantly, the obtained temperature- independent low glass-like lattice thermal conductivity of 2.27 W/(m∙K) was significantly reduced by 68.2–21.4% compared with the majority values ranging from 7.16 W/(m∙K) at 300 K to 2.89 W/(m∙K) at 1073 K of SrTiO3-based polycrystal system. The temperature independence of thermal conductivity over the whole range of 323–1073 K realizes the concept of ‘phonon-glass electron crystal’. Evidence strongly confirmed that large lattice distortion, TiO6 octahedral twist, dislocations, and complex strain field coexisted by Raman, HRTEM combined with GPA analysis in the high-entropy perovskite structures.
AB - High-entropy oxides with complex compositions can be designed to lower the thermal conductivity of SrTiO3-based thermoelectric materials to optimize their properties. High-entropy (Sr0.25Ca0.25Ba0.25RE0.25)TiO3 (RE=Nd, Sm, Eu, Gd, Dy, Ho) ceramics were designed to systematically investigate the effects of critical average ionic radius (rA̅), atomic size disorder factor (δAr), and the mass difference factor (δAm) of A-site elements on the single-phase formation, disorder microstructure, and the thermoelectric properties. The successful synthesis of single-phase perovskite-type ceramics of (Sr0.25Ca0.25Ba0.25Nd0.25)TiO3, (Sr0.25Ca0.25Ba0.25Sm0.25)TiO3, and (Sr0.25 Ca0.25Ba0.25Eu0.25)TiO3 by a solid-state reaction method were reported. When rA̅ <1.377 Å, indicator of δAr≥ 12.86, and δAm≥ 18.6, the pyrochlore phase of Gd2Ti2O7, Dy2Ti2O7, and Ho2Ti2O7 precipitated. Importantly, the obtained temperature- independent low glass-like lattice thermal conductivity of 2.27 W/(m∙K) was significantly reduced by 68.2–21.4% compared with the majority values ranging from 7.16 W/(m∙K) at 300 K to 2.89 W/(m∙K) at 1073 K of SrTiO3-based polycrystal system. The temperature independence of thermal conductivity over the whole range of 323–1073 K realizes the concept of ‘phonon-glass electron crystal’. Evidence strongly confirmed that large lattice distortion, TiO6 octahedral twist, dislocations, and complex strain field coexisted by Raman, HRTEM combined with GPA analysis in the high-entropy perovskite structures.
KW - High-entropy ceramics
KW - Perovskite
KW - Thermal conductivity
KW - Thermoelectric materials
UR - http://www.scopus.com/inward/record.url?scp=85143693475&partnerID=8YFLogxK
U2 - 10.1016/j.jallcom.2022.168366
DO - 10.1016/j.jallcom.2022.168366
M3 - Article
AN - SCOPUS:85143693475
SN - 0925-8388
VL - 937
JO - Journal of Alloys and Compounds
JF - Journal of Alloys and Compounds
M1 - 168366
ER -