Papers by Author: Xiao Dong Li

Abstract: Ce0.5Ti0.5O2 ion storage films were prepared by using sol–gel routes employed butyltitanate（Ti(OC4H9)4） and cerium nitrate（Ce(NO3)3•6H2O） as main initial materials. Structural, optical and electrochemical properties were investigated by XRD, SEM, cyclic voltammetry curves and utraviolet visible spectroscopy in this work. Ce0.5Ti0.5O2 ion films contained crystallization CeO2 and amorphous TiO2, and had large ion storage capacity. Its injection of charge density was high to 12.01 mC•cm-2 and K value was 0.75. It had better cyclic reversibility and high transparency, which kept colorless and transparent during the whole injection and extraction process of Li+. Light insert ion storage films of Ce0.5Ti0.5O2 has important significance in the preparation of electrochromic device.

Abstract: YAG nanopowders were synthesized by a co-precipitation method using ammonium hydrocarbonate and ammonia water as the precipitants respectively. The influences of precipitants on chemical compositions, phase transformation and sinterability of the prepared powders, and transmittance of the vacuum-sintered YAG ceramics were studied. The sinterability of powders synthesized using ammonium hydrocarbonate as precipitant is better than that with ammonia water. Pure YAG phase can be obtained by calcining the hydrate precursor at 1200°C, while some impurity phases exist when calcining the carbonate precursor at the same temperature. Transparent YAG ceramics were fabricated by vacuum sintering at 1700°C for 5 h using the YAG nanopowders, and their in-line transmittance is about 60% in the visible light range.

Abstract: Open-cell Al O ceramic foams with uniform cell structures and dense cell struts were fabricated by centrifugal slip casting using the plant seeds as the templates. The rheological characteristic of Al O slurries with up to 50 vol.% solid content was investigated. The shrinkage matching between the Al O green compact and the plant seeds during drying was studied. The effect of solid contents of slurries on change of green density of cell struts along the height of compacts was analyzed. The drying and sintering schedule of Al O green cakes were studied. The results indicated mass segregation of Al O particles with different sizes during centrifugal process was negligible for slurries with high solid loadings with 50 vol. %. The cell struts of green bodies had high density of 63.8% TD. After sintered at 1500 °C for 2 h, the final products had dense cell struts with high sintered density of 98.9%TD and homogeneous microstructure. The porosity and compressive strength of sintered products was 66.5% and 5.26 MPa, respectively.

Abstract: Hydroxyapatite (HA) powder was synthesized by a sol-gel method with Ca(OH)2 and H3PO4 as reactants. The HA granules were then coated with TiH2 powder using a mechanical mixing method. The HA-TiH2 material system produced HA-Ti composites after hot-pressing at 1050°C. The HA-Ti composites are mainly composed of HA and Ti, with small amounts of Ca2P2O7 and Ca3(PO4)2 phases. Fracture toughness and bending strength are 2.4 MPa·m1/2 and 54.3 MPa, respectively for the HA-20vol%Ti composite, higher than those of the pure HA ceramic. The improvement in properties is because of the unique 3D network structure of Ti, which is an ideal reinforcement structure for the weak and brittle HA. According to ISO/TR 7405-1984, hemolysis test was performed to evaluate the blood compatibility of the material. The results show that the hemolysis rate of the HA-20vol%Ti composite is 0.56%. Relative growth rates (RGR) of L-929 cells soaked after 6 days in the HA-20vol%Ti group, pure Ti group, black group and pure Pb group were 132%, 100%, 90% and 6% respectively, while the level of cytotoxicity was grade 0 in HA-Ti composite group. These results imply that the HA-20vol%Ti composite has good biocompatibility and bioactivity.