| In this paper, a simple coprecipitation technique had been successfully applied for preparation of pure ultrafine single phase Ta2O5-based solid electrolyte powders. Ammonia spirit was used to precipitate Mn+(Ti4+,Zr4+,Fe3+) and Ta5+ cations as hydroxides simultaneously. The effects of precipitating process conditions (such as consistency of reactant, content of PEG, pH and rate of titration) on the coprecipitation of the products and the calcination temperature were studied and the optimum process conditions for the manufacture of powders were determined. DTA, XRD, TEM, grain-size distribution meter and some other experiment methods had been employed to characterize the products. The effluent treatment was researched by lime and evaporation, and the content of F- was tested by ion chromatograph.The Ta2O5 -based solid oxide electrolyte of intermediate temperature used in fuel cells was investigated systematically. The effects of doping on the electrical, thermal expansibility and microstructure morphology were evaluated. Some optimum electrolyte compositions were selected by the experimental results and theoretical analysis. The conductivity, thermal expansibility and microstructure morphology were investigated by insulated resistance device, thermal dilatometer, X-ray diffraction, scanning electron microscopy.The research results show:The solid electrolyte materials had good performance, lower sintering temperature, higher density and conductivity by coprecipitation technique using for the preparation of solid eiectroiyte materials. The method had many merits of work simplification, inexpensive and easy expanding.Adequate Ta and R(Ti,Zr,Fe) was dissolved and diluted with water to 0.01mol/L, then the above solution mixture was added into excessive ammonia spirit and PEG was 1.5wt%. The pH was maintained 11.5 to ensure completion of the reaction. After filtering, the precipitate was washed several times with distilled water and was dehydrated with absolute ethyl alcohol, then dried in an oven at 85℃for 12-16 h, then calcined at 700℃for 1 h. At last the grain diameter of primary particle is about 30-50nm.The lime was used for removeing fluorinion in waste water treatment. The concentration of fluorinion was cut down when the addition of lime was changed from 5g/L to 30g/L. The concentration of fluorinion was 37.19mg/L while the addition of lime was 10g/L and the concentration was 28.56mg/L while the addition of lime was 20g/L. When the addition of lime was 20g/L, the concentration of fluorinion was cut down with the stewing time increment. The concentration of fluorinion was 28.56mg/L when the stewing times were 10 hours, in this case, the achievement on reducing fluoride was obvious. When the stewing times were 24 hours, the concentration of fluorinion was 23.11mg/L.The evaporation was used for recovery processing of ammonia in waste water treatment. The coefficient of recovery increases with the tempreratures increment, and then decreases. The coefficient of recovery reached 72.0% in all tested temperature.The TiO2+Ta2O5 system displays low thermal expansibility and high conductivity in a wide range of composition. The sample with 7.7mol% TiO2 had the maximum conductivity of 3.28×10-1S/cm at 800℃, and the conductivity was overreached 10-2S/cm at 600℃. The thermal expansibility coefficient changes from 2.48×10-6 to 2.88×10-6K-1 when the doping increases from 2.0mol% to 12.0mol%. The cell parameters decrease with the increasing of doping, then increase and last decrease. The structure of system is orthorhombic system.In the Fe2O3+Ta2O5 system, the sample with 8.5mol% Fe2O3 had the maximum conductivity of 1.25×10-1S/cm at 800℃. The thermal expansibility coefficient changes from 3.02×l0-6 to 3.89×10-6K-1 when the doping increases from 4.0mol% to 16.0mol%. The cell parameters increase with the increasing of doping, and then decrease. The structure of system is orthorhombic system.In the TeO2+Ta2O5 system, the sample with 7.0mol% TeO2 had the maximum conductivity of 4.79×10-2S/cm at 800℃. The thermal expansibility coefficient changes from 2.95×10-6 to 3.27×10-6K-1 when the doping increases, from 6.0mol% to 9.0mol%. The cell parameter of a increases with the increasing of doping, then decreases; the b and c decrease. The structure of system is orthorhombic system.In the ZrO2+Ta2O5 system, the sample conductivity changes from 1.14×10-4 to 5.25×10-4S/cm at 800℃and the thermal expansibility coefficient changes from 2.31×10-6 to 3.03×l0-6K-1 when the doping increases from 7.0mol% to 11.0mol%. The cell parameter of a decreases with the increasing of doping, then increases, the b and c are just the reverse. The structure of system is orthorhombic system.
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