Influence Of Crystalline Phase Research Articles

The dynamic mechanical characteristics of Zr-based bulk metallic glasses and composites

In the current study, Zr-based metallic glass matrix composites (MGMCs) were prepared by doping high-melting point of tantalum powders and investigated by dynamic mechanical analysis. The results suggest that the relaxation processes are changed by modifying the chemical composition. The influence of crystalline phase on the dynamic mechanical response of Zr-based MGMC has been analyzed. The master curves of loss modulus can be well fitted by the Kholrausch-Williams-Watts (KWW) model, decreasing of the parameter βKWW implies that the Zr-based MGMC doped with more tantalum powders has higher dynamic heterogeneity. To better understand the dynamic mechanical properties of the MGMCs, quasi-point defects (QPD) theory is adopted, the kinetic characteristics of glass transition of Zr-based MGMCs are analyzed in a quantitative manner. The experimental results provide an insightful information on the complex structural relaxation of the metallic glass matrix composite.

Nanoscale Conductance in Lead Phthalocyanine Thin Films: Influence of Molecular Packing and Humidity

The influence of crystalline phase and disorder on vertical charge transport in nonplanar metallophthalocyanines is studied by depositing thin films of shuttlecock molecules, lead phthalocyanine (PbPc), and SnPc on various substrates such as highly oriented pyrolytic graphite (HOPG), silicon, and gold and investigating the structural and electrical characteristics of the films. The films represent three cases of crystalline packing such as monoclinic, triclinic, and disordered phases, directed by the substrate–molecule interactions and intermolecular interactions. Theoretical calculations are performed to understand the molecular orientations on the substrate and give insights into the possible origin of ordered and disordered packing. Vertical charge transport in the films is studied by employing conducting atomic force microscopy and compared with bulk electrical measurements. It is revealed that the monoclinic phase of PbPc on HOPG exhibits two orders of magnitude higher conductance than silicon or gol...

Influence of crystalline phase and defects in the ZrO2 nanoparticles synthesized by thermal plasma route on its photocatalytic properties

The photocatalytic activity of pure ZrO2 samples, prepared by a thermal plasma route, and characterized by X-ray diffraction technique was tested for the degradation of methylene blue, which is known to be a hazardous dye. Although, all these samples synthesized at different operating pressures of the thermal plasma reactor showed the photocatalytic activity; the sample synthesized at 1.33bar of operating pressure showed the highest photocatalytic activity. The blue shift in the band gap of monoclinic phase, as observed from the photo-absorption spectroscopy, may be attributed to the enhanced photocatalytic activity. The existence of different defect states and their concentration as, inferred from the photo-absorption measurements were also found to be responsible for the enhanced photocatalytic activity of the as synthesized samples.

Influence of the crystalline phase and surface area of the TiO2 support on the CO oxidation activity of mesoporous Au/TiO2 catalysts

The influence of the TiO2 crystalline phase and of the surface area on the activity and stability/deactivation behavior of structurally well-defined mesoporous Au/TiO2 catalysts with comparable Au loading in the CO oxidation reaction was investigated by kinetic measurements under differential reaction conditions and by in situ DRIFTS. The crystalline phase and surface area of the TiO2 substrate were controlled by the pH and the type of the structure-directing surfactants applied in the synthesis. Au loading of the mesoporous oxides was performed by the same deposition–precipitation procedure for all catalysts. The resulting trends in the CO oxidation behavior, including the TOF based activities and the stability/deactivation behavior are discussed.

Thermal diffusivity of reaction-sintered AlON/Al 2O 3 particulate composites

The thermal diffusivity of particulate composites prepared by sintering compacts of Al 2O 3 with additions of 1–25 mol% AlN under 1-atm nitrogen gas pressure at 1600–1800 °C has been measured over the range 25–1000 °C using the laser flash method. The diffusivity of reaction-sintered materials decreased on addition of AlN, mainly due to the formation of an AlON phase. This effect was less pronounced with increasing temperature and furthermore, it appeared to be related to the temperature-dependence of thermal resistance. The influence of crystalline phase, microstructure and physical property on the thermal diffusivity of AlON/Al 2O 3 was characterized. The thermal conductivity of the sintered materials at room temperature behaved in a similar manner to the thermal diffusivity.

Influence of crystalline phase of zeolitic catalysts on efficiency of m-xylene and ethylbenzene isomerization

Influence of crystalline phase of zeolitic catalysts on efficiency of m-xylene and ethylbenzene isomerization