Low Temperature Synthesis of (Pb,La)(Zr,Sn,Ti)O_3 Powders by Citrate Process

Lead lanthanum zirconate stannate titanate （PLZST） powders with homogeneous composition were synthesized at a relatively low temperature of 650 ℃ by a citrate process based on the Pechini method. Clear aqueous solutions were prepared from inorganic salts, and citric acid was added as a chelating agent to attain precursor sols. Dried gel-precursors were calcined at different temperatures for various time. The perovskites powders were obtained at 650 ℃ for 1 hour. XRD and SEM results show that the powders were single-phase and ultrafine particles.

Nanosized Nickel Oxides Derived from the Citrate Gel Process and Performances for Electrochemical Capacitors

Nanosized nickel oxide powders were prepared by thermal decomposition of the nickel citrate gel precursors. The thermal decomposition and powder materials derived from calcination of these gel precursors with various ratios of citric acid （CA） to nickel at different temperatures and times were characterized by thermal analysis （TG/DTA）, scanning electron microscopy （SEM）, x-ray diffraction （XRD）, and measurement of specific surface area （BET） with porosity analyses. The optimized processing conditions of calcination temperature 400℃ for 1 hour with the CA/Ni ratio of 1.2, were determined to produce the nanosized nickel oxide pow- ders with a high specific surface area of 181 m^2/g, nanometer particle sizes of 15-25 nm, micro-pore diameter distribution between 4-10 nm. The capacitance characteristics of the nanosized nickel oxide electrode in various concentrations of KOH solutions were studied by the cyclic voltammetry （CV） exhibiting both a double-layer capacitance and a faradaic pseudocapacitance. The nanosized nickel oxide electrode shows a high cyclic stability and is promising for high performance electrochemical capacitors.

Nanosized Ni-Mn Oxides Prepared by the Citrate Gel Process and Performances for Electrochemical Capacitors

Nanosized Ni-Mn oxide powders have been successfully citrate gel precursors. The powder materials derived from prepared by thermal decomposition of the Ni-Mn calcination of the gel precursors with various molar ratios of nickel and manganese at different temperatures and time were characterized using thermal analysis （TG-DSC）, scanning electron microscopy （SEM）, X-ray diffraction （XRD） and Brunauer-Emmet-Teller （BET）. The optimized processing conditions of calcination at 400℃ for 1 h with Ni/Mn molar ratio 6 were proved to produce the nanosized Ni-Mn oxide powders with a high specific surface area of 109.62 m^2/g and nanometer particle sizes of 15-30 nm. The capacitance characteristics of the nanosized Ni-Mn oxide electrode in various concentrations of KOH solutions were studied by the cyclic voltammetry （CV） and exhibited both a doublelayer capacitance and a Faradaic capacitance which could be attributed to the electrode consisting of Ni-Mn oxides and residual carbons from the organic gel thermal decomposition. A specific capacitance of 194.8 F/g was obtained for the electrode at the sweep rate of 10 mV/s in 4 mol/L KOH electrolyte and the capacitor showed quite high cyclic stability and is promising for advanced electrochemical capacitors.