Browsing by Author "Zhao, W"

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    A high-temperature performing and near-zero energy loss lead-free ceramic capacitor
    (Royal Society of Chemistry, 2023-08-21) Li, D; Xu, D; Zhao, W; Avdeev, M; Jing, H; Guo, Y; Zhou, T; Liu, W; Wang, D; Zhou, D
    A pivotal obstacle of obtaining dielectric ceramics with large recoverable energy density (Wrec) and ultrahigh energy efficiency (η) desperately needs to be overcome for the development of advanced energy storage devices for high pulsed power systems, especially via an environment-friendly lead-free method. Here we report a series of lead-free dielectric bulk ceramics for high-temperature energy storage capacitors with near-zero energy loss. Confirmed by aberration-corrected scanning transmission electron microscopy and phase-field simulation, a judiciously designed heterostructure in which rhombohedral and tetragonal polar nanoregions are embedded in a cubic paraelectric matrix was constructed. The combination of the increased breakdown strength and the minimized polarization hysteresis, respectively, based on the heterostructure design and repeated rolling process, contributes to a large Wrec of 10.28 J cm−3 and a record-high η of 97.11%, superior to the reported lead-free bulk ceramics. Based on such structure-induced advantages, the wide-temperature stability (25–200 °C) and high performance (Wrec ∼ 6.35 ± 9.1% J cm−3, η ∼ 94.82% ± 3.4%) of the dielectric ceramics broaden their application in high temperature energy storage systems. This work conspicuously contributes to the development of the next generation high-temperature capacitors and suggests a new paradigm that may stimulate the development of higher-performance energy storage dielectrics. Facebook Twitter LinkedIn YouTube© Royal Society of Chemistry 2024
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    Magnetotransport and Berry phase tuning in Gd-doped Bi2Se3 topological insulator single crystals
    (American Physical Society, 2022-05-01) Chen, L; Li, SS; Zhao, W; Bake, A; Cortie, DL; Wang, XL; Karel, J; Li, H; Zheng, RK
    The Berry phase is an important concept in solids, correlated to the band topology, axion electrodynamics, and potential applications of topological materials. Here, we investigate the magnetotransport and Berry phase of rare earth element Gd-doped Bi2Se3 (Gd:Bi2Se3) topological insulators (TIs) at low temperatures and high magnetic fields. Gd:Bi2Se3 single crystals show Shubnikov-de Haas (SdH) oscillations with nontrivial Berry phase, while Bi2Se3 single crystals show zero Berry phase in SdH oscillations. A fitting of the temperature-dependent magnetization curves using the Curie-Weiss law reveals that the Gd dopants in the crystals show paramagnetism in the 3-300 K region, indicating that the origin of the Berry phase is not long-range magnetic ordering. Moreover, Gd doping has limited influence on the quantum oscillation parameters (e.g., frequency of oscillation, area of Fermi surface, effective electron mass, and Fermi wave vectors) but has a significant impact on the Hall mobility, carrier density, and band topology. Our results demonstrate that Gd doping can tune the Berry phase of TIs effectively, which may pave the way for the future realization of many predicted exotic transport phenomena of topological origin. ©2022 American Physical Society