Zirui Jia

Dielectric and thermal properties of epoxy resins with TiO 2 nanowires

Epoxy based composites with reinforced dielectric properties were successfully synthesized by using TiO2 nanowires as inorganic filler. TiO2 nanoparticle/epoxy composites were also prepared as a contrast. TiO2 nanowires were synthesized by a hydrothermal method, with an average diameter of 50xa0nm and a length of 5xa0µm. TiO2 nanoparticles were purchased with average diameter of ~60xa0nm. Scanning electron microscopy images show that two types of fillers are both homogeneously dispersed in the matrix. Although the specific surface area of TiO2 nanoparticles is about twice of that of TiO2 nanowires, remarkable improved dielectric constant, enhanced electrical and thermal conductivity, higher space charge accumulation and stronger charge carrier mobility were observed in nanowire filled epoxy resin at the same filler content. Meanwhile, nanowires composites exhibit excellent glass transition temperature and thermal stability. These results indicated that the geometry of filler had a profound impact on the performance of epoxy composites, and nanowire filling is more effective than nanoparticle filling to enhance the properties of epoxy resin.

Progress in low-frequency microwave absorbing materials

Electromagnetic wave equipment and devices working at low frequency of 0.5–8xa0GHz have been extensively used in wireless data communication systems, local area network, household appliances and so on. It is found that the extensive use of such devices have a terrible pollution to their surroundings and moreover threaten the health of human being by weakening biological immune systems, breaking DNA strands, promoting cancers. A key solution to this problem is to develop materials that are able to attenuate the harmful electromagnetic waves pollution. This review aims at summarizing the progresses obtained in conventional materials and new emerging structures for microwave absorption at low frequency. The ultimate aim of these materials is to realize a wider effective absorption frequency bandwidth (fE) at a thinner coating thickness (d). Typical and well-received component and construction of composite, synthesis methods, and fE are summarized in several tables in detail. The different characteristics of different types of absorbing materials are given much attention in this review.

Cr 2 O 3 nanocrystal anode materials with improved cyclic stability for lithium ion batteries

The cyclic stability of Cr2O3 is very poor due to the large volume change during lithiation/delithiation. In this study, we have found that Cr2O3 nanocrystals synthesized by using a simple hydrothermal method can improve its cyclic stability. Sample calcined at 430xa0°C has uniform size, compact structure and high crystallization degree. These Cr2O3 nanocrystals exhibit a stable cyclic performance of 185 mAhxa0g−1 after 100 cycles at 100xa0mAxa0g−1. It is useful in real life, such as providing power consumption for minitype device, etc.