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711 results on '"Zhang, Bo-ping"'

103. Design and Fabrication of Segmented GeTe/(Bi,Sb)2Te3 Thermoelectric Module with Enhanced Conversion Efficiency.

Author

Pei, Jun, Shi, Jian‐Lei, Li, Hezhang, Jiang, Yilin, Dong, Jinfeng, Zhuang, Hua‐Lu, Cai, Bowen, Su, Bin, Yu, Jincheng, Zhou, Wei, Zhang, Bo‐Ping, and Li, Jing‐Feng

Subjects
HEAT radiation & absorption, FINITE element method, COPPER, POWER density, LOW temperatures, ANTIMONY
Abstract

GeTe and (Bi,Sb)2Te3 are two representative thermoelectric (TE) materials showing maximum performance at middle and low temperature, respectively. In order to achieve higher performance over the whole temperature range, their segmented one‐leg TE modules are designed and fabricated by one‐step spark plasma sintering (SPS). To search for contact and connect layers, the diffusion behavior of Fe, Ni, Cu, and Ti metal layers in GeTe is studied systematically. The results show that Ti with a similar linear expansivity (10.80 × 10−6 K−1) to GeTe, has low contact resistance (3 µΩ cm2) and thin diffusion layer (0.4 µm), and thus is an effective metallization layer for GeTe. The geometric structure of the GeTe/(Bi,Sb)2Te3 segmented one‐leg TE module and the ratio of GeTe to (Bi,Sb)2Te3 are determined by finite element simulation method. When the GeTe height ratio is 0.66, its theoretical maximum conversion efficiency (ηmax) can reach 15.9% without considering the thermal radiation and thermal/electrical contact resistance. The fabricated GeTe/(Bi,Sb)2Te3 segmented one‐leg TE module showed a ηmax up to 9.5% with a power density ≈ 7.45 mW mm−2, which are relatively high but lower than theoretical predictions, indicating that developing segmented TE modules is an effective approach to enhance TE conversion efficiency. [ABSTRACT FROM AUTHOR]

Published
2023
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143. High-performance BiFeO3BaTiO3lead-free piezoceramics insensitive to off-stoichiometry and processing temperature

Author

Tang, Yu-Cheng, Yin, Yang, Song, Ai-Zhen, Li, He-Zhang, and Zhang, Bo-Ping

Abstract

It is well-known that the performance of BiFeO3BaTiO3(BF-BT) ceramics is sensitive to composition, calcining and sintering temperature (Tcaland Tsint) due to the formation of Bi25FeO39and/or Bi2Fe4O9impurities and/or the volatilization of Bi2O3. We report remarkably stable electrical properties over the range of −0.03 ≤ x ≤ 0.05 and 930 °C ≤ Tsint≤ 970 °C in 0.7Bi(1+x)FeO3-0.3BaTiO3ceramics prepared by one-step process. This method avoids the thermodynamically unstable region of BiFeO3and prevents the formation of Bi25FeO39and/or Bi2Fe4O9impurities even when the addition of α-Bi2O3raw material is intentionally deficient or rich to make off-stoichiometric BF-BT, thus greatly improving the robustness of compositional and processing. Rhombohedral-pseudocubic phase coexists in all ceramics, and their CR/CPCfraction are 48.0/52.0–50.6/49.4 and 55.9/44.1–56.6/43.4 when xincreases from −0.05 ≤ x ≤ 0 to 0.01 ≤ x ≤ 0.05. The stable electrical properties of d33 = 180–205 pC/N, Pr = 17.9–23.8 μC/cm2, and TC = 485–518 °C are achieved. The maximum d33T/d33RTof BF-BT is twice that of soft PZT, superior to most the-state-of-art lead-free ceramics. Our results provide a synthesis strategy for designing high performance piezoelectric materials with good stability and easy industrialization.

Published
2023
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