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Featured researches published by Ming-He Wu.


Molecular Physics | 2016

Theoretical investigations on the g factors and local structures for Cu2+ in the ZnX (X= O, S and Se) nanocrystals

Guo-Liang Li; Shao-Yi Wu; Bao-Hua Teng; Ming-He Wu

ABSTRACT The g factors and local structures for Cu2+ in the ZnX (X = O, S and Se) nanocrystals at room temperature are theoretically investigated by the perturbation calculations for a tetragonally distorted tetrahedral 3d9 cluster in a consistent way, and the isotropic g factor is predicted for the ZnS:Cu2+ nanocrystals at room temperature. The bond angles θ between the four equivalent Cu2+−X2− bonds and the C4 axis are found to be about 1.26°, 1.24° and 1.07°, respectively, larger in the ZnO, ZnS and ZnSe nanocrystals than that (θ0 ≈ 54.74°) for an ideal tetrahedron, inducing tetragonally compressed tetrahedra. The declining tendency (ZnO > ZnS > ZnSe) of the tetragonal angular distortion Δθ (= θ − θ0) can be ascribed to the decreasing strength of the dynamic Jahn–Teller effect via the vibration interactions of the [CuX4]6− groups due to the weakening Cu2+−X2− bonding. The isotropic g factors are attributable to the appropriate Δθ due to the dynamic Jahn–Teller effect and the internal stress. The slightly increasing (ZnO < ZnS < ZnSe) g factors can be illustrated by the declining cubic field parameter Dq, angular distortion Δθ and covalency factor N of the systems. GRAPHICAL ABSTRACT


Magnetic Resonance in Chemistry | 2018

Analysis on the local structures for 3d1 impurities (Ti3+ and V4+) in KTiPO4

Chang-Chun Ding; S.-Y. Wu; Li-Juan Zhang; Yong-Qiang Xu; Zhi-Hong Zhang; Ming-He Wu; Bao-Hua Teng

Making use of the perturbation formulae for 3d1 ions (Ti3+ and V4+) under orthorhombically compressed octahedra, the spin Hamiltonian parameters (g factors: gx, gy, gz and hyperfine structure constants: Ax, Ay, Az) and local structures of the 3d1 impurity centres C1, C2, and C3 in KTiOPO4 crystals are theoretically analyzed in a consistent way. The remarkable local distortions (i.e., the relative axial compression ratios 11.2%, 7.0%, and 5.5% along Z axis and the relative planar bond length variation ratios 15.9%, 7.0%, and 6.0%) are obtained for the [Ti2O6]9− cluster on Ti2 site and [VO6]8− clusters on Ti1 and Ti2 sites, respectively, in view of the Jahn–Teller effect. The above local orthorhombic distortion parameters in the impurity centres are found to be more significant than the host Ti1 and Ti2 sites in pure KTiOPO4. The sequences (C1 > C2 > C3) of the local orthorhombic distortion parameters ρ and τ are in accordance with those of the axial and perpendicular anisotropies Δg and δg of g factors, respectively.


Philosophical Magazine | 2017

Investigations on the local structures of Cu2+ at various BaO concentrations in 59B2O3–10K2O–(30−x)ZnO–xBaO–1CuO glasses

Jia-Rui Jin; Shao-Yi Wu; Jian Hong; Shi-Nan Liu; Min-Xian Song; Bao-Hua Teng; Ming-He Wu

Abstract The local structures and electron paramagnetic resonance (EPR) parameters for Cu2+ in 59B2O3–10K2O–(30−x)ZnO–xBaO–1CuO (BKZBC) glasses are theoretically investigated with distinct modifier BaO concentrations x (= 0, 6, 12, 18, 24 and 30 mol %). The clusters are found to undergo the relative tetragonal elongations of about 13.5 and 5.0% at zero and higher BaO concentrations. The concentration dependences of the measured d–d transition bands, g factors and A// are suitably reproduced from the Fourier type functions or sign functions of the relevant quantities with x by using only six adjustable parameters. The features of the EPR parameters and the local structures of Cu2+ are analysed in a consistent way by considering the differences in the local ligand field strength and electronic cloud admixtures around Cu2+ under addition of Ba2+ with the highest ionicity and polarisability. The present theoretical studies would be helpful to the researches on the structures, optical and EPR properties for the similar potassium barium zinc borate glasses containing copper with variation concentration of modifier BaO.


European Journal of Physics | 2014

The magnetic field generated by a rotating charged polygon

Songlin Wan; Bao-Hua Teng; Xiangyu Chen; Hao Fu; Yefeng Li; Ming-He Wu; Shao-Yi Wu; E A Balfour

The magnetic field along the symmetry axis of a regular polygon carrying a uniform electric charge on its edges is calculated systematically when the polygon is rotated about this axis of symmetry. A group of circular current-carrying coils arranged concentrically about the axis of the polygon has been designed to simulate the magnetic field characteristics of the rotating charged polygon. The magnetic field of the simulated coils is measured using the PASCO magnetic field sensor. The results show that the theoretical calculation agrees well with the experimental results.


Zeitschrift für Naturforschung A | 2017

The DFT Calculations of Structures and EPR Parameters for the Dinuclear Paddle-Wheel Copper(II) Complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) as Powder or Single Crystal

Chang-Chun Ding; Shao-Yi Wu; Yong-Qiang Xu; Li-Juan Zhang; Zhi-Hong Zhang; Qin-Sheng Zhu; Ming-He Wu; Bao-Hua Teng

Abstract Density functional theory (DFT) calculations of the structures and the Cu2+ g factors (gx, gy and gz ) and hyperfine coupling tensor A (Ax , Ay and Az ) were performed for the paddle-wheel (PW)-type binuclear copper(II) complex {Cu2(μ2-O2CCH3)4}(OCNH2CH3) powder and single crystal. Calculations were carried out with the ORCA software using the functionals BHandHlyp, B3P86 and B3LYP with five different basis sets: 6-311g, 6-311g(d,p), VTZ, def-2 and def2-TZVP. Results were tested by the MPAD analysis to find the most suitable functional and basis sets. The electronic structure and covalency between copper and oxygen were investigated by the electron localisation function and the localised orbital locator as well as the Mayer bond order for the [CuO5] group. The optical spectra were theoretically calculated by the time-dependent DFT module and plotted by the Multiwfn program for the [CuO5] group and reasonably associated with the local structure in the vicinity of the central ion copper. In addition, the interactions between the OCNH2CH3, NH3 and H2O molecules and the uncoordinated PW copper(II) complex were studied, and the corresponding adsorption energies, the frequency shifts with respect to the free molecules and the changes of the Cu–Cu distances were calculated and compared with the relevant systems.


Zeitschrift für Naturforschung A | 2016

Theoretical Studies of the Spin Hamiltonian Parameters and Local Distortions for Cu2+ in Alkaline Earth Lead Zinc Phosphate Glasses

Bo-Kun Wang; Shao-Yi Wu; Zi-Yi Yuan; Zi-Xuan Liu; Shi-Xin Jiang; Zheng Liu; Zi-Jian Yao; Bao-Hua Teng; Ming-He Wu

Abstract The spin Hamiltonian parameters and local structures are theoretically studied for Cu2+-doped alkaline earth lead zinc phosphate (RPPZ, R=Mg, Ca, Sr, and Ba) glasses based on the high-order perturbation calculations for a tetragonally elongated octahedral 3d9 cluster. The relative elongation ratios are found to be ρ≈3.2%, 4.4%, 4.6%, and 3.3% for R=Mg, Ca, Sr, and Ba, respectively, because of the Jahn-Teller effect. The whole decreasing crystal-field strength Dq and orbital reduction factor k from Mg to Sr are ascribed to the weakening electrostatic coulombic interactions and the increasing probability of productivity of nonbridge oxygen (and hence increasing Cu2+–O2− electron cloud admixtures) under PbO addition, respectively, with increasing alkali earth ionic radius. The anomalies (the largest Dq and the next highest k among the systems) for R=Ba are attributed to the cross linkage of this large cation in the network. The overall increasing order (Mg≤Ba<Ca<Sr) of ρ is largely due to the decreasing crystal-field strength Dq and hence the decreasing force constant of the Cu2+–O2− bonds. The present studies would be helpful to understand local structures and the influences on the optical properties of RPPZ glasses containing copper dopants.


European Journal of Physics | 2015

Hysteresis in the phase transition of chocolate

Ruilong Ren; Qunfeng Lu; Sihua Lin; Xiaoyan Dong; Hao Fu; Shao-Yi Wu; Ming-He Wu; Bao-Hua Teng

We designed an experiment to reproduce the hysteresis phenomenon of chocolate appearing in the heating and cooling process, and then established a model to relate the solidification degree to the order parameter. Based on the Landau–Devonshire theory, our model gave a description of the hysteresis phenomenon in chocolate, which lays the foundations for the study of the phase transition behavior of chocolate.


Physics and Chemistry of Minerals | 2014

Interpretation of the EPR parameters through investigating the local lattice deformations for the two Pt3+ centers in ZnWO4

Chang-Chun Ding; Shao-Yi Wu; Min-Quan Kuang; Zhi-Hong Zhang; Bao-Hua Teng; Ming-He Wu


Journal of Physics and Chemistry of Solids | 2015

An investigation on the defect structures and spin Hamiltonian parameters for the two orthorhombic Ti3+ centers in ZnWO4

Chang-Chun Ding; Shao-Yi Wu; Qing-Sheng Zhu; Zhi-Hong Zhang; Bao-Hua Teng; Ming-He Wu


Journal of Lightwave Technology | 2018

FDTD simulation: refractive index and single-object sensing using a whispering-gallery-modes microring resonator

Zhi-Hong Zhang; Si-Hui Shang; Mu-Neng Li; Shao-Yi Wu; Qin-Sheng Zhu; Ming-He Wu; Bao-Hua Teng

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Bao-Hua Teng

University of Electronic Science and Technology of China

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Shao-Yi Wu

University of Electronic Science and Technology of China

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Zhi-Hong Zhang

University of Electronic Science and Technology of China

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Chang-Chun Ding

University of Electronic Science and Technology of China

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Li-Juan Zhang

University of Electronic Science and Technology of China

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Qin-Sheng Zhu

University of Electronic Science and Technology of China

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Guo-Liang Li

University of Electronic Science and Technology of China

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Hao Fu

University of Electronic Science and Technology of China

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Li Peng

University of Electronic Science and Technology of China

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Li-Na Wu

University of Electronic Science and Technology of China

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