The silicate oxyapatites Ca2-3xLa8+2x□x（SiO4）6O2 （x=0, 0.17, 0.33, 0.50, 0.67） was synthesized via a sol-gel method at low temperature. The apatite phases have been characterised by X-ray diffraction （XRD）, conducting properties was studied by electrical chemistry impedance spectroscopy （EIS）. The conductivity of La9.33□0.67（SiO4）6O2 is 1.58 × 10-3 S·cm-1 at 700 ℃, it is higher about 4 270 times than that of Ca2La8（SiO4）6O2, the activation energy is decreasing from 1.37 eV to 0.84 eV. With cation vacancies increasing,the conducting mechanism is gradually translation from a direct linear pathway free oxygen ion conduction to a curve pathway interstitial oxygen ion conduction. The electrical conductivities is almost independent of the oxygen partial pressure, this suggests that the oxyapatites exhibited almost pure O2- ion conduction over a wide range of oxygen partial pressure.
Nafion/TiO2 composite membranes were prepared by in-situ chemical reaction method using Ti(OC4H9)4 and Nafion 117 as raw materials. The membranes were characterized by UV, FTIR-ATR and XRD, respectively. Methanol permeability and water uptake were investigated as a function of TiO2 contents. The conductivity of the membranes was measured under water vapor pressure (2.644 7 kPa) or in dry atmospheres. The XRD results showed that the titanium dioxide in Nafion membranes were crystallized in anatase phase with an average crys- taline diameter of 3.0 nm. The water uptake of the composite membranes was larger than that of the pure Nafion○ membrane when the TiO2 loading was within 14wt%. The methanol permeability of the membrane decreased as the TiO2 loading increased. The addition of 3wt% TiO2 to Nafion○ membranes improved the conductivity in dry measurement conditions. The proton conductivity of the composite membrane increased greatly after the hy- drothermal treatment at 160 ℃ for 2 hours.
