Synthesis and magnetic property of iron ions-doped hydroxyapatite.

Magnetic Hydroxyapatite (HAP) particles were successfully synthesized at different concentration of Fe2+ by a co-precipitation method. The influences of concentration of doped ions and calcination temperature on the morphology and magnetic property were studied. The iron ions-doped HAP still kept its structure similar to conventional HAP and no second phases were detected. Results indicated that the doping of iron ions decreased the crystallinity and inhibited the c-axis growth and promoted the a-axis growth. HAP particles incorporated with 10% and 50% iron ions exhibited superparamagnetic and with 30% iron ions exhibited weak ferromagnetic characters. In addition, calcination temperature also increased the remnant.

Ni2+ doped indium oxide nanocubes: doped contents inducing transferring of their intrinsic magnetisms.

A series of Ni2+ doped indium oxide nanocubes with different Ni2+ contents (nominally from 3 at.% to 20 at.%) were prepared by direct solvothermal method. We found that the highest Ni2+ doped percentage was 20 at.% in the experiment and crystalline sizes of these Ni2+ doped indium oxide specimens linearly increased with increments of doped contents and then decreased. Meanwhile, their magnetisms were also transferred from ferromagnetism to paramagnetic properties due to the stronger Ni-O-Ni paramagnetic chemical bonds. HRTEM, SAED and XRD further confirmed their magnetic properties were intrinsic and not caused by second impure phases.

Air activation of charcoal monoliths for capacitive energy storage.

Charcoal monoliths derived from waste wood were activated with air for the application of electrochemical capacitor electrodes and an insight was given into the activation mechanism. The mild air activation is effective and pollution-free compared to the common chemical activation using KOH etc. for the preparation of crack-free carbon monoliths. The activation process was controlled by altering the activation temperature and time, and their effects on the nanostructure of charcoal monoliths were studied. As the activation temperature or time increased, air eroded the defective surface of charcoal layer-by-layer, with the oxygen atoms being introduced by chemisorption and oxidation reactions and removed by dehydration and decomposition reactions. Meanwhile, micro-pores were produced. The electrode activated at 300 °C for 1 h, with a specific surface area of 567 m2 g-1 and a high micro-porosity of 86%, exhibited a specific capacitance of 203 F g-1 and 35.5 F cm-3. Moreover, it presented a higher total capacitance of 3.6 F cm-2 than most reported pellet electrodes. These findings give a reasonable picture of the air activation process and are instructive to prepare activated carbon monoliths under an oxidizing environment.

Effects of silica sol on the microstructure and mechanical properties of CaSiO3 bioceramics.

CaSiO3 ceramics were fabricated with silica sol addition by pressureless sintering. The effects of silica sol on phase composition, microstructure and mechanical properties of CaSiO3 ceramics were investigated. The silica sol additive was found to be effective in speeding up pore elimination, improving the grain growth, decreasing the sintering temperature and shortening the sintering time. When the amount of SiO2 was 5wt%, a flexural strength of 186.2MPa was achieved with an open porosity of 3.9%. The main crystal phase was ß-CaSiO3 below sintering temperature of 1150°C.

Effects of h-BN addition on microstructures and mechanical properties of ß-CaSiO3 bioceramics.

The main purpose of this study consists in investigating the effects of h-BN addition on the sinterability of ß-CaSiO3 (ß-CS) bioceramics. ß-CS bioceramics with different contents of h-BN were prepared at the sintering temperature ranging from 800°C to 1100°C. The results showed that h-BN can be successfully used as sintering additive by being oxidized to form low melting point B2O3 related glassy phase and enhanced the flexural strength by the formation of rod-like ß-CS grains. ß-CS bioceramics with 1wt% h-BN sintered at 1000°C revealed flexural strength and fracture toughness of 182.2MPa and 2.4MPam(1/2) respectively, which were much higher than that of pure ß-CS bioceramics (30.2MPa, 0.53MPam(1/2)) fabricated in the same processing condition.

The improved mechanical properties of ß-CaSiO3 bioceramics with Si3N4 addition.

The motivation of this study is to investigate the effect of Si3N4 addition on the sinterability of ß-CaSiO3 ceramics. ß-CaSiO3 ceramics with different content of Si3N4 were prepared at the sintering temperature ranging from 1000°C to 1150°C. The results showed that Si3N4 can be successfully used as sintering additive by being oxidized to form SiO2. The ß-CaSiO3 ceramics with 3wt% Si3N4 sintered at 1100°C revealed flexural strength, hardness and fracture toughness of 157.2MPa, 4.4GPa and 2.3MPam(1/2) respectively, which was much higher than that of pure ß-CaSiO3 ceramics (41.1MPa, 1.0GPa, 1.1MPam(1/2)). XRD analysis and SEM observation indicated that the main phase maintained to be ß-phase after sintering.