Browsing by Author "Wang, W"
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- ItemAtomistic characterisation of graphite oxidation and thermal decomposition mechanism under isothermal and non-isothermal heating scheme(Elsevier B. V., 2022-07) Cordeiro, IMDC; Yuen, ACY; Wang, W; Yang, W; Chan, QN; Yeoh, GHThe oxidation of graphene-based material (i.e. graphite, graphene) is a reaction of immense importance owing to its extensive industrial application (i.e. nanocomposites, flame retardants, energy storage). Although immense experimental works were carried out for identifying the thermal degradation and oxidation process of graphene, they generally lack atomistic-level observation of the surface reactions, thermal formation pathways from solid to product volatiles and structural evolutions during oxidation. To analyse the favourable properties of graphene from its carbon-chain molecular structure viewpoint, it is essential to investigate graphene-based materials at an atomic level. This study bridges the missing knowledge by performing quantitative reactive forcefield coupled molecular dynamics simulation (MD-ReaxFF) to determine the oxidation kinetics of graphite under computational characterisation schemes with temperatures ranging from 4000 K to 6000 K. The kinetics parameters (i.e. activation energy) were extracted through proposed numerical characterisation methods and demonstrated good agreement with the thermogravimetric analysis experiments and other literature. Activation energy at 193.84 kJ/mol and 224.26 kJ/mol were extracted under the isothermal scheme by two distinct characterisation methods, achieving an average relative error of 11.3 % and 2.5 % compared to the experiment data, which is 218.60 kJ/mol. In comparison, the non-isothermal simulations yielded 214.53 kJ/mol, with a significant improvement on the average relative error of 1.86 %. © 2022 Elsevier B.V.
- ItemAuthor Correction: A one-third magnetization plateau phase as evidence for the Kitaev interaction in a honeycomb-lattice antiferromagnet(Springer Nature, 2023-09-10) Shangguan, Y; Bao, S; Dong, ZY; Xi, N; Gao, YP; Ma, Z; Wang, W; Qi, Z; Zhang, S; Huang, Z; Liao, J; Zhao, X; Zhang, B; Cheng, S; Xu, H; Yu, DH; Mole, RA; Murai, N; Ohira-Kawamura, S; He, LH; Hao, J; Yan, QB; Song, F; Li, W; Yu, SL; Li, JX; Wen, JSCorrection to: Nature Physics, published online 25 September 2023. In the version of the article initially published, the affiliation of Zhen Ma, now reading School of Materials Science and Engineering, Hubei Normal University, Huangshi, China, appeared incorrectly. This has been updated in the HTML and PDF versions of the article. n the version of the article initially published, the affiliation of Zhen Ma, now reading School of Materials Science and Engineering, Hubei Normal University, Huangshi, China, appeared incorrectly. This has been updated in the HTML and PDF versions of the article. © 2024 Springer Nature Limited.
- ItemDisorder-induced spin-liquid-like behavior in kagome-lattice compounds(American Physical Society (APS), 2020-12-15) Ma, Z; Dong, ZY; Wu, S; Zhu, Y; Bao, S; Cai, Z; Wang, W; Shangguan, Y; Wang, J; Ran, K; Yu, DH; Deng, GC; Mole, RA; Li, HF; Yu, SL; Li, JX; Wen, JSQuantum spin liquids (QSLs) are an exotic state of matter that is subject to extensive research. However, the relationship between the ubiquitous disorder and the QSL behaviors is still unclear. Here, by performing comparative experimental studies on two kagomé-lattice QSL candidates, Tm3Sb3Zn2O14 and Tm3Sb3Mg2O14, which are isostructural to each other but with strong and weak structural disorder, respectively, we show unambiguously that the disorder can induce spin-liquid-like features. In particular, both compounds show dominant antiferromagnetic interactions with a Curie-Weiss temperature of -17.4 and -28.7 K for Tm3Sb3Zn2O14 and Tm3Sb3Mg2O14, respectively, but remain disordered down to about 0.05 K. Specific-heat results suggest the presence of gapless magnetic excitations characterized by a residual linear term. Magnetic excitation spectra obtained by inelastic neutron scattering (INS) at low temperatures display broad continua. All these observations are consistent with those of a QSL. However, we find in Tm3Sb3Zn2O14, which has strong disorder resulting from the random mixing of the magnetic Tm3+ and nonmagnetic Zn2+, that the low-energy magnetic excitations observed in the specific-heat and INS measurements are substantially enhanced compared to those of Tm3Sb3Mg2O14, which has much less disorder. We believe that the effective spins of the Tm3+ ions in the Zn2+/Mg2+ sites give rise to the low-energy magnetic excitations, and the amount of the occupancy determines the excitation strength. These results provide direct evidence of the mimicry of a QSL caused by disorder. ©2020 American Physical Society.
- ItemEpitaxial nickel rerrocyanide stabilizes Jahn–Teller distortions of manganese ferrocyanide for sodium‐ion batteries(Wiley, 2021-06-06) Gebert, F; Cortie, DL; Bouwer, JC; Wang, W; Yan, Z; Dou, SX; Chou, SLManganese‐based Prussian Blue, Na2−δMn[Fe(CN)6] (MnPB), is a good candidate for sodium‐ion battery cathode materials due to its high capacity. However, it suffers from severe capacity decay during battery cycling due to the destabilizing Jahn–Teller distortions it undergoes as Mn2+ is oxidized to Mn3+. Herein, the structure is stabilized by a thin epitaxial surface layer of nickel‐based Prussian Blue (Na2−δNi[Fe(CN)6]). The one‐pot synthesis relies on a chelating agent with an unequal affinity for Mn2+ and Ni2+ ions, which prevents Ni2+ from reacting until the Mn2+ is consumed. This is a new and simpler synthesis of core–shell materials, which usually needs several steps. The material has an electrochemical capacity of 93 mA h g−1, of which it retains 96 % after 500 charge–discharge cycles (vs. 37 % for MnPB). Its rate capability is also remarkable: at 4 A g−1 (ca. 55 C) it can reversibly store 70 mA h g−1, which is also reflected in its diffusion coefficient of ca. 10−8 cm2 s−1. The epitaxial outer layer appears to exert an anisotropic strain on the inner layer, preventing the Jahn–Teller distortions it normally undergoes during de‐sodiation. © 1999-2024 John Wiley & Sons, Inc