Jiawei Sheng

X-ray irradiation on the soda-lime container glass.

X-ray irradiation induced defects in the commercial soda-lime container glass were studied by means of optical spectrophotometer and ESR. The induced color might be applied to producing recyclable glasses. The nonbridging oxygen hole centers (NBOHCs) were mainly responsible for the irradiation induced absorptions at 431 and 627 nm of glass. The absorption at 305 nm was attributed to the trapped electron. The induced deep color can be kept for longer than 7 months, but can be almost bleached at 300 degrees C for 20 min.

Magnetic properties of La-Zn substituted Sr-hexaferrites by self-propagation high-temperature synthesis

Abstract The La-Zn substituted SrM-type ferrites with the composition of Sr 1-x La x Fe 12-x Zn x O 19 (x=0-0.4) were prepared by self-propagating high-temperature synthesis (SHS). The single SrM phase was detected by XRD in the as-received samples by controlling the Fe contents in the reagents. The substitution of La 3+ and Zn 2+ obviously increased the magnetic properties of the as-prepared samples. The maximum improvements of B r , H cb and ( BH ) m were 14.4%, 15.3% and 30.7%, respectively compared with that of the samples without La-Zn substitution. Microstructure observation by SEM showed that the SHS method benefited forming the better particle features and achieving the higher H cj in comparison with the traditional firing method.

Fading behavior of X-ray induced color centers in soda-lime silicate glass.

The X-ray induced color centers in soda-lime silicate glass were unstable at room temperature. There was a rapid fading at short-term stage and a slow fading at long-term stage. In the short-term stage, both first-order and second-order fading kinetics played roles in the fading process, while only the first-order fading controlled the long-term stage fading.

Nanosized gold clusters formation in selected areas of soda-lime silicate glass

Nanosized gold clusters were developed in a gold-doped soda-lime silicate glass after X-ray irradiation followed by annealing, which provided an alternative way of forming metallic nanoclusters in glass to ion implantation. The formation of gold nanoclusters can be controlled by irradiation time or annealing time.

Dry grinding effect on pyrophyllite-quartz natural mixture and its influence on the structural alternation of pyrophyllite.

Infrared spectroscopy (IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), and high-resolution transmission electron microscopy (HRTEM) with energy dispersive X-ray analysis (EDS) were used to investigate the evolution of mechanical destruction of the pyrophyllite structure and final ground products upon grinding with a laboratory planetary ball mill. The raw ore used in this present work was mainly composed of pyrophyllite and quartz. This pyrophyllite was more resistant toward mechanical destruction, and the crystalline order of pyrophyllite was not completely destroyed until grinding for 240 min with a 20:1 of weight ratio of the balls to powder. The existing crystalline phase in the final ground product was found to be quartz, which served as the associated phase in the original pyrophyllite mineral. The rate of destruction of pyrophyllite structure depended on the types of chemical bonds. Additionally, increasing the intensity of grinding resulted in acceleration of the mechanically induced amorphization of the pyrophyllite structure, whereas the associated quartz grains contributed to the deceleration of the amorphization of pyrophyllite.

Coloration and decoloration of glasses by photo-irradiation and heat treatment for easily recycled glass products

We have been developing a technique of coloration and decoloration of glasses by photo-irradiation and heat-treatment for application to easily recyclable colored glass products. The mechanisms of the photo-induced coloration of glasses used in this research are a) the photo-induced defects (color centers) formation, b) the photo-induced change in oxidation state of ions, and c) the photo-induced formation of nanoparticles in glasses. The subjects for application of these phenomena to recyclable colored-glass products are presented. The research examples for each mechanism are presented in this paper as follows: 1) the effect of the doped Fe ions on the optical density and stability of coloration due to color centers, 2) the coloration by the change in oxidation state, (formula available in paper) and 3) the reversible coloration and decoloration for an Ag single-doped glass.

Nanoscale structure and formation mechanism of the aragonite fibers in the ligament of Hyriopsis Cumingii shell

The ligament of bivalve molluscs is known for its exceptional mechanical properties. In the present work, we investigated the nanoscale structure and composition of the aragonite fibers in the inner ligament of the freshwater shell Hyriopsis Cumingii, using high-resolution transmission electron microscope coupled with selected area electron diffraction, field-emission scanning electron microscope, and X-ray diffraction. The sample was found to exhibit cobble-like nanograins that were the basic building blocks to construct individual needle-shaped aragonite fibers in the ligament, which are generally different in sizes and shapes. The individual aragonite fibers were confirmed to be polycrystalline. In addition, twin stacking faults have been observed in the aragonite fibers of the ligament. These newly identified structural properties enhance our understanding of the formation mechanisms of bivalve ligaments and provide new guidelines to design and synthesis advanced functional materials for biomedical applications.