【作者】 李景超；

【导师】 李金平；

【作者基本信息】 大连理工大学 ， 材料学， 2009， 硕士

【摘要】 本论文以金属Ta和R（R分别为Ti,Fe和Zr金属）为原料,氢氟酸为溶剂,氨水为沉淀剂,采用反向滴定化学共沉淀法制备超细氧化钽基固体电解质粉体;研究了反应物浓度、分散剂PEG10000的用量、pH值、干燥条件、焙烧温度及其它因素对氧化物粉体制备工艺的影响,确定了最佳工艺参数;并用差热仪（DTA）、透射电镜（TEM）、离心粒度分布仪、激光粒度仪等实验手段对固体电解质粉体有关性质进行了测试和表征;采用石灰法、蒸发法对含氟含氮废水进行了有效处理,用离子色谱仪检测了处理后废水中氟离子的含量。将上述方法制备的粉体经模压成型后,用高温烧结法制备了氧化钽基中温氧化物固体电解质；探讨了不同量的掺杂物对固体氧化物电解质材料电学性能、热膨胀性和显微结构的影响；其中二元TeO₂+Ta₂O₅系统由于金属Te难溶解于氢氟酸,采用了直接氧化物混合法制备了电解质;经过实验和理论分析,优选了固体电解质组分和制备工艺,采用电导率测试仪、热膨胀仪（TED）、X-射线衍射仪（XRD）、扫描电子显微镜（SEM）等仪器测试了固体电解质的电导性、热膨胀性和晶体结构。结果表明:1、采用反向滴定化学共沉淀法制备的氧化钽基固体电解质粉体性能优良,降低了固体电解质烧结温度、提高了电解质的致密度和电导率:该方法具有工艺简单、成本低廉、易于扩大等优点,优化的工艺条件为:反应物浓度0.01mol/L,分散剂PEG10000用量1.5%（质量分数）,最终反应溶液pH=11.5,反应温度为室温条件下制备的前驱体,经离心机分离、无水乙醇脱水和85℃干燥后,于700℃煅烧1h制备出固体氧化物电解质粉体,颗粒粒径约为30-50nm。2、在氟离子含量为1.27g/L的废水处理过程中,随着静置时间和石灰乳加入量的增加,废水中氟离子浓度逐渐降低;当静置时间为10h,石灰投加量为10g/L时,上清液很快降到[F^-]:37.19mg/L,当石灰投加量为20g/L时,上清液[F^-]=28.56mg/L;当静置时间为24h时,石灰乳投加量为20g/L,上清液中[F^-]=23.11mg/L。除氟后的废水用蒸发法提取氨,保温时间不变时,随着保温温度的升高,回收率先是增大后降低,在处理温度范围（65-85℃）之内,回收率都达到了72.0%以上。3、在氧化钽基固体电解质材料中,二元TiO₂+Ta₂O₅系统在一定组成范围内存在固溶体,表现出高的电导率和低的热膨胀系数;掺杂TiO₂含量为7.7mol%时,电导率（800℃）有最大值为3.28×10^-1S/cm;在600℃时,其电导率超过了10^-2S/cm;掺杂TiO₂含量x=2.0-12.0mol%范围,系统的热膨胀系数变化为2.48x10^-6-2.88×10^-6K^-1;此系统固体电解质的晶体类型属于正交晶系,单位晶胞参数a、b、c值随掺杂量增加,先增大后减小,在x=7.7-8.0mol%时达到了最大值,与电导率（800℃）最大值对应。二元Fe₂O₃+Ta₂O₅系统,在Fe₂O₃含量为8.5mol%时,电导率（800℃）达到了最大值1.25×10^-1S/cm;Fe₂O₃含量x=4.0-16.0mol%时,系统的热膨胀系数变化为3.02×10^-6-3.89×10^-6K^-1,略高于二元TiO₂+Ta₂O₅系统;此系统的晶体类型属于正交晶系,晶胞参数a、b、c值随掺杂量增加,先增大后减小,x=8.0-8.5mol%时有最大值。二元TeO₂+Ta₂O₅系统中,在TeO₂含量为7.0mol%时,电导率（800℃）达到最大值,为4.79×10^-2S/cm;在TeO₂含量x=6.0-9.0mol%范围,系统热膨胀系数为2.95×10^-6-3.27x10^-6K^-1;此系统的晶体类型属于正交晶系,随掺杂量增加,晶胞参数a先增大后减小,b、c逐渐增大。二元ZrO₂+Ta₂O₅系统中,随着ZrO₂含量（x=7.0-11.0mol%）的增加,热膨胀系数变化较小,为2.31×10^-6-3.03×10^-6K^-1;电导率（800℃）变化范围为1.14×10^-4-5.25×10^-4S/cm;此系统的晶体类型属于正交晶系,随掺杂量增加,晶胞参数a先减小后增大,b、c则先增大后减小,均在x=8.0mol%时有最小值或最大值。更多还原

【Abstract】 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.更多还原