Browsing by Author "Zhou, D"

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    Controlling spin orientation and metamagnetic transitions in anisotropic van der Waals antiferromagnet CrPS4 by hydrostatic pressure
    (Wiley, 2022-02) Peng, Y; Lin, Z; Tian, G; Yang, J; Zhang, P; Wang, F; Gu, P; Liu, X; Wang, CW; Avdeev, M; Liu, F; Zhou, D; Han, R; Shen, P; Yang, W; Liu, S; Ye, Y; Yang, J
    Controlling the phases of matter is a central task in condensed matter physics and materials science. In 2D magnets, manipulating spin orientation is of great significance in the context of the Mermin–Wagner theorem. Herein, a systematic study of temperature‐ and pressure‐dependent magnetic properties up to 1 GPa in van der Waals CrPS4 is reported. Owing to the temperature‐dependent change of the magnetic anisotropy energy, the material undergoes a first‐order spin reorientation transition with magnetic moments realigning from being almost parallel with the c axis in the ac plane to the quasi‐1D chains of CrS6 octahedra along the b axis upon heating. The spin reorientation temperature is suppressed after applying pressure, shifting the high‐temperature phase to lower temperatures with the emergence of spin‐flop transitions under magnetic fields applied along the b axis. The saturation field increases with pressure, indicating the enhancement of interlayer antiferromagnetic coupling. However, the Néel temperature is slightly reduced, which is ascribed to the suppression of intralayer ferromagnetic coupling. The work demonstrates the control of spin orientation and metamagnetic transitions in layered antiferromagnets, which may provide new perspectives for exploring 2D magnetism and related spintronic devices. © 2021 Wiley-VCH GmbH.
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    Expanding the applications of the ilmenite mineral to the preparation of nanostructures: TiO2 nanorods and their photocatalytic properties in the degradation of oxalic acid
    (Wiley-Blackwell, 2013-01-14) Tao, T; Chen, Y; Zhou, D; Zhang, HZ; Liu, S; Amal, R; Sharma, N; Glushenkov, AM
    The mineral ilmenite is one of the most abundant ores in the Earth's crust and it is the main source for the industrial production of bulk titanium oxide. At the same time, methods to convert ilmenite into nanostructures of TiO2 (which are required for new advanced applications, such as solar cells, batteries, and photocatalysts) have not been explored to any significant extent. Herein, we describe a simple and effective method for the preparation of rutile TiO2 nanorods from ball-milled ilmenite. These nanorods have small dimensions (width: 520 nm, length: 50100 nm, thickness: 25 nm) and possess large specific surface areas (up to 97 m2?g-1). Dissolution/hydrolysis/precipitation is proposed as a growth mechanism. The nanorods were found to have attractive photocatalytic properties in the degradation of oxalic acid. Their photocatalytic activity is close to that of the benchmark Degussa P25 material and better than that of a commercial high-surface-area rutile powder. © 2013, Wiley-Blackwell
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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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    Ultralow loss and high tunability in a non‐perovskite relaxor ferroelectric
    (Wiley, 2022-11-10) Li, R; Xu, D; Avdeev, M; Zhang, L; Chen, XF; Gou, GY; Wang, D; Liu, WF; Zhou, D
    Dielectric ceramics are fundamental for electronic systems, including energy storages, microwave applications, ultrasonics, and sensors. Relaxor ferroelectrics show superb performance among dielectrics due to their high efficiency and energy density by the nature of nanodomains. Here, a novel non‐perovskite relaxor ferroelectric, Bi6Ti5WO22, with ultralow loss, ≈10−3, highly tunable permittivity, ≈2200 at room temperature with 40% tunability and the superparaelectric region at room temperature is presented. The actual crystal structure and the nanodomains of Bi6Ti5WO22 are demonstrat Various‐temperature neutron powder diffraction and in situ high‐resolution transmission‐electron‐microscopy illustrate the twinning effect, subtle structure change and micro‐strain in the material influenced by temperature, manifesting the actual crystal structure of Bi6Ti5WO22. Compared with dielectric loss of BaTiO3‐based dielectric tunable materials, the loss of Bi6Ti5WO22 is more than an order of magnitude lower, which makes it exhibit a figure of merit (≈240), much higher than that of conventional dielectric tunable materials (< 100), endorse the material great potential for direct applications. The present research offers a strategy for discovering novel relaxor ferroelectrics and a highly desirable material for fabricating energy storage capacitors, microwave dielectrics, and ultrasonics. © 1999-2024 John Wiley & Sons, Inc