Structural Distortion and Defects in Ti_3AlC_2 irradiated by Fe and He Ions

Ti_3AlC_2 samples are irradiated in advance by 3.5 MeV Fe-ion to the fluence of 1.0×10^（16） ion/cm^2,and then are implanted by 500 keV He-ion with the fluence of 1.0×10^（17） ion/cm^2 at room temperature.The irradiated samples are investigated by grazing incidence x-ray diffraction（GIXRD） and transmission electron microscopy（TEM）.GIXRD results show serious structural distortion,but without amorphization in the irradiated samples.Fe-ion irradiation and He-ion implantation create much more serious structural distortion than single Fe-ion irradiation.TEM results reveal that there are a large number of defect clusters in the damage region,and dense spherical He bubbles appear in the He depositional region.It seems that the pre-damage does not influence the growth of He bubbles,but He-ion implantation influences the pre-created defect configurations.

Comparative Study on the Defects of Kaolinite from America,Brazil and China Applied for Paper Coating：XRD and Refinement by Rietveld Method

Three kaolinite samples applied for paper coating were collected from America（KA）,Brazil（KB）,and China（KC）,respectively.Parameters such as average bond length of Si-O and Al-O（1（Si-O） and1（（Al-O）））,tetrahedral rotation angles（α）,changes of tetrahedral flattemng angles（τ） and octahedral flattemng angles（ψ） comparative to ideal angle,particle layer thickness（T） and basal z corrugation（Δz） were analyzed by XRD and Rietveld method.The experimental results indicated that △z（KA）〉△z（KC）〉△z（KB）.KB has a regular structure and KA has a disorder structure,α（KA）〉α（KC）〉α（KB）,△τ（KA）〉△τ（KC）〉△τ（KB）,and △ψ（KA）〉△ψ（KB）〉△ψ（KC）.KA has unstable tetrahedron and octahedron.KB and KC have stable tetrahedron and octahedron,respectively.In the process of manufacture,kaolinite structure may be broken from places with unstable tetrahedron and octahedron.l（Si-O）（KA） 〉l（Si-O）（KB）〉l（Si-O）（KC） and 1（A1-O）KA〉1（A1-O）（KC）〉1（A1-O）（KB）.What only considered is the effect of bond length,KA may be most easily broken in the manufacture.Compared with bond lengths of KA and KB,Si-O,and Al-O of KB and KC may be easily broken,respectively.T（KA）

Effect of coating modification of cordierite carrier on catalytic performance of supported NiMnO_3 catalysts for VOCs combustion

NiMnO3 perovskite catalysts supported on cordierite modified by CexZr（1-x）O2 coatings were prepared using impregnation and sol-gel methods for catalytic combustion of single/double component VOCs at different concentrations and GHSV of 15,000 h^（-1）, which were characterized by BET, XRD, SEM, FT-IR, H2-TPR and O2-TPD. After coating modification, the specific surface area of catalysts is improved obviously.Among the catalysts, the Ce（0.75）Zr（0.25）O2 coating modified NiMnO3 catalyst exhibits the best catalytic activity for VOCs combustion with 95.6% conversion at 275 ℃ and has stable activity when catalyst is embalmed at 800 ℃. In addition, the catalyst also presents the excellent water-resistant and conversion stability over time-on-stream condition. The reason is that Ce（0.75）Zr（0.25）O2 coating can promote more lattice distortion and defects and smaller crystal size, which improve oxygen transfer capability and dispersion of active component.