Wanqiang Liu

Preparation and wear resistance of Ti–Zr–Ni quasicrystal and polyamide composite materials

Ti–Zr–Ni icosahedral quasicrystal powders (Ti-QC), prepared by mechanical alloying and then annealing in a vacuum furnace, were used as a novel filler material in polyamide 12 (PA12). The melt processability of the composite was studied using a Haake torque rheometer. This indicates that PA12/Ti-QC composites can be melt-processed into a wear-resistant material. Further, these composites, fabricated by compression molding, were tested in sliding wear against a polished bearing steel counterface. The results from wear testing show that the addition of Ti-QC filler to PA12 enhances wear resistance and reduces volume loss by half compared with neat PA12. Furthermore, it is found that the hardness of the composite increases with increasing content of Ti-QC filler. In addition, PA12/Ti-QC composites exhibit a slightly higher crystallization temperature and better thermal stability than PA12. These combined results demonstrate that Ti-QC filler may be a desirable alternative when attempting to increase the wear resistance of PA12.

Responsivity enhancement of ZnO/Pt/MgZnO/SiO2 and MgZnO/Pt/ZnO/SiO2 structured ultraviolet detectors by surface plasmons in Pt nanoparticles

The structured (ZnO/Pt/MgZnO/SiO2) ultraviolet detector was fabricated and demonstrated to investigate how metallic nanoparticles localized surface plasmons contribute when the two different dielectrics surrounded simultaneously. After sandwiching the Pt nanoparticles between the double layers of MgZnO and ZnO, the extinction was increased largely. Meanwhile, by examining the dependence of MgZnO and ZnO peak responsivity enhancement ratio, we found that MgZnO was significantly larger than ZnO. The interpretation by considering is that the localized surface plasmons of energy match with MgZnO which is superior to ZnO. In order to validate this conclusion and make it more accurate, we also fabricated the MgZnO/Pt/ZnO/SiO2 structure. Our work suggests that rational integration of double-layer and metal nanoparticles is a viable approach to perceive localized surface plasmons with double-layer ultraviolet detectors, which may help to advance optoelectronic devices.

Exploring the geometrical structures of X©BnHnm [(X, m) = (B, +1), (C, +2) for n = 5; (X, m) = (Be, 0), (B, +1) for n = 6] by an electronic method

A series of singlet and triplet wheel-type clusters obtained through an electronic method, i.e., adding two and four electrons into X©BnHnm [(X, m) = (B, +1), (C, +2) for n = 5; (X, m) = (Be, 0), (B, +1) for n = 6], have been studied theoretically. With the increase of the number of electrons, the sizes of peripheral boron rings tend to decrease due to the increase of negative charges on the boron rings. The results of the kinetic stability and the electronic stability suggest that the triplet C©B5H5 and singlet Be©B6H6 are stable and may be detected experimentally. Nucleus-independent chemical shift and molecular orbital analysis reveal that some wheel-type clusters with the planar ring possess aromaticity properties that are attributed to the delocalized π electrons conforming to the Huckel rule, i.e. 4n + 2 for singlets or 4n for triplets. These findings from this work are significant for designing novel wheel-type clusters.

Influence of heat treatment on electrochemical properties of Ti1.4V0.6Ni alloy electrode containing icosahedral quasicrystalline phase

Abstract The structures and electrochemical properties of the Ti 1.4 V 0.6 Ni ribbon before and after heat treatment are investigated systematically. The structure of the sample is characterized by X-ray powder diffraction analysis. Electrochemical properties including the discharge capacity, the cyclic stability and the high-rate discharge ability are tested. X-ray powder diffraction analysis shows that after heat treatment at 590 °C for 30 min, all samples mainly consist of the icosahedral quasicrystal phase (I-phase), Ti 2 Ni phase (FCC), V-based solid solution phase (BCC) and C14 Laves phase (hexagonal). Electrochemical measurements show that the maximum discharge capacity of the alloy electrode after heat treatment is 330.9 mA·h/g under the conditions that the discharge current density is 30 mA/g and the temperature is 30 °C. The result indicates that the cyclic stability and the high-rate discharge ability are all improved. In addition, the electrochemical kinetics of the alloy electrode is also studied by electrochemical impedance spectroscopy (EIS) and hydrogen diffusion coefficient ( D ).

Controlled response wavelength shifting in ultraviolet photodetectors based on double-layer films

By integrating ZnO and MgZnO films onto a quartz substrate (both films with the same growth time), the ultraviolet photodetectors (Au/ZnO/MgZnO/SiO2 and Au/MgZnO/ZnO/SiO2 structured photodetectors) have been fabricated. The responsivity peaks blue-shift from 380 to 370u2009nm (380 to 375u2009nm) by increasing the bias voltage in 1.0u2009h (1.5u2009h) photodetectors, which is denoted by the growth time of one layer of the films. More interestingly, the Au/MgZnO/ZnO/SiO2 photodetectors shift the same response wavelength range at smaller bias voltages than the Au/ZnO/MgZnO/SiO2 photodetectors. The results are well-rationalized in term of the role played by the double-layer structure.

Electrochemical hydrogen storage characteristics of TiVNi–quasicrystalline composite materials

The Ti1.4V0.6Ni ribbon alloy and VTZN (V5Ti9Zr26.7Ni38Cr5Mn16Sn0.3) alloy ingot are prepared by melt–spinning technique and induction levitation melting technique, respectively. The Ti1.4V0.6Ni + 20 wt.% VTZN mixture powders are synthesised by ball–milling the above prepared alloy ingots, and their structures and the electrochemical hydrogen storage properties are investigated. It is found that the icosahedral quasicrystal, FCC and BCC structural solid solution phase are all presented in the composite material. The maximum electrochemical discharge capacity of the composite electrode is 308.2 mAh/g at the discharge current density of 30 mA/g and 303 K. In addition, the electrode made of Ti1.4V0.6Ni and AB3 composite holds better high–rate discharge ability than that of Ti1.4V0.6Ni.