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Theoretical studies on the structural, electronic and optical properties of BeZnO alloys

Xiong D. P., Zhou S. L., He M., Wang Q., Zhang W., Feng Z. Y.

Materials Science Poland

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2020

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Vol. 38, No. 4

629--636

EN

The structural, electronic and optical properties of BexZn1−xO alloys were studied using the density functional theory and Hubbard-U method. Uo,p = 10.2 eV for O 2p and UZn,d = 1.4 eV for Zn 3d were adopted as the Hubbard U values. For BexZn1−xO alloys, the lattice constants a and c decrease linearly as Be concentration increases, the bandgap increases with a large bowing parameter of 6.95 eV, the formation enthalpies have the maximum value with Be concentration at 0.625, corresponding to the possible Be concentration to form phase separation. These calculations comply well with the experimental and other theoretical results. Furthermore, optical properties, such as dielectric function ∈(ω), reflectivity R(ω), absorption coefficient α(ω), were calculated and discussed for BexZn1−xO alloys with the incident photon energy ranging from 0 eV to 30 eV.

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Enhancing SO2 removal efficiency by lime modified with sewage sludge in a novel integrated desulfurization process

Qin L., Han J., Chen W., Liu Z., He M., Xing F.

Environment Protection Engineering

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2017

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Vol. 43, nr 4

17--27

EN

In China, the sintering process annually emitted around 1.5 million t SO2, representing 70% of SO2 produced from the iron and steel industry. Lime based sorbent was modified with municipal sewage sludge (MSS) and the influence of the modification on the desulfurization efficiency was investigated in a laboratory-scale novel integrated desulfurization (NID) reactor. The properties of modified sorbent were characterized by the Brunauer–Emmett–Teller (BET) analyzer and X-ray fluorescence (XRD) analyzer. BET surface area was increased from 17.48 to 46.68 m2g–1. when the MSS/lime ratio increased from 0 to 0.08. Ca4Al8Si8O32, Ca1.5SiO3.5, Na2Si2O5 and CaSiO3 found in the modified lime benefited for the increase of the BET surface area and pore volume. The effects of sewage sludge/CaO weight ratio, calcination temperature and hydration time on the desulfurization efficiency were also studied. SO2 removal efficiency was increased from 88.7% to 97.3% after using the lime modified with sewage sludge.

3

On the Interaction of Resonance And Bragg Scattering Effects for the Locally Resonant Phononic Crystal with Alternating Elastic and Fluid Matrices

Yuan B., Chen Y., Jiang M., Tang S., He M., Tu M.

Archives of Acoustics

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2017

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Vol. 42, No. 4

725--733

EN

Three-dimensional (3D) locally resonant phononic crystals (LRPCs) are studied with the aim of optimising the sub-wavelength band gaps of such composites. By analysing their effective acoustic properties, it has been found that the effective acoustic speed of the composite will drop to zero when local resonance arise, and will increase monotonically when Bragg scattering effects occur. Moreover, if the matrix is a low-shear-speed medium, local resonators can significantly reduce the effective acoustic speed of the composite and, therefore, lower the frequency where Bragg scattering effects occur. Hence, a specific LRPC with alternating elastic and fluid matrices is proposed, whose resonance and Bragg gaps are already close in frequency. The fluid matrix behaves as a wave filter, which prevents the shear waves from propagating in the composite. By using the layer-multiple-scattering theory, the coupling behaviour of local resonance and Bragg scattering band gaps has been investigated. Both gaps are enhanced when they move closer to each other. Finally, a gap-coupled case is obtained that displays a broad sub-wavelength band gap. Such proposal excels at the application of underwater acoustic materials since the arrangement of structure can be handily adjusted for tuning the frequency of coupled gap.

4

Synthesis and Magnetism of Nickel(II) Binuclear Complexes with Oxamide-N,N'-diacetic Acid

Han K., Tian Z., Wei K., Ma S., Lu L., Meng X., Yang X., He M., Gao J.

Polish Journal of Chemistry

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1999

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Vol. 73, nr 9

1451-1456

EN

Three novel -oxamidato binuclear complexes have been synthesized. The temperature dependences of the magnetic susceptibilities. These results are commensurate with antiferromagnetic interaction between the adjacent metal ions.