【作者】 朱剑莉；

【导师】 马桂林；

【作者基本信息】 苏州大学 ， 无机化学， 2007， 硕士

【摘要】 高温质子导体因其具有特殊的质子导电功能,在固体氧化物燃料电池,气体传感器,有机物的氢化和脱氢,氢的电解制备、分离和提纯、常压合成氨等能源变换及薄膜反应器方面有着重要的应用价值和广泛的应用前景。1994年,Ishihara首次发现Sr²⁺和Mg²⁺掺杂的LaGaO₃基陶瓷是优良的氧离子导体,已成为较理想的中温固体氧化物燃料电池（IT-SOFC）固体电解质候选材料之一。但在过去十多年中,人们的研究集中在LaGaO₃基陶瓷的氧离子导电性能上。最近,本人所在课题组首次报道了La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-α吨在氢气气氛中具有优良的质子导电性。但至今尚未见到Sr²⁺和Zn²⁺掺杂的LaGaO₃基陶瓷质子导电性的报道;此外,LaGaO₃基陶瓷的传统制备方法是固相法,但固相法制备的LaGaO₃基陶瓷常含有杂相。本研究采用高温固相法、溶胶—凝胶法（Sol-Gel法）和微乳液法等方法合成了La_0.9Sr_0.1Ga_1-xM_xO_3-α(M=Mg²⁺,Zn²⁺)陶瓷;分别采用交流阻抗谱、气体浓差电池和电化学分子透过等多种电化学方法研究了样品在600～1000℃下各种气氛中的离子导电性能。本研究的主要成果如下:（1）采用三种方法合成了La_0.9Sr_0.1Ga_1-xM_xO_3-α吨陶瓷,其中,溶胶—凝胶法和微乳液法合成的陶瓷样品为单一斜方钙钛矿相结构,成功地解决了固相法合成的镓酸镧基陶瓷存在的杂相问题;（2）首次发现La_0.9Sr_0.1Ga_1-xZn_xO_3-α吨陶瓷在氢气气氛中具有优良的质子导电性能,其质子迁移数为1,高于700℃时的质子电导率均在10^-2S·cm^-1以上;（3）发现La_0.9Sr_0.1Ga_1-xM_xO_3-α吨陶瓷在湿润空气气氛中是混合离子（质子+氧离子）导体;（4）发现La_0.9Sr_0.1Ga_1-xM_xO_3-α陶瓷在干燥含氧气气氛中是纯的氧离子导体;（5）比较了Sr、Zn²⁺和Sr、Mg²⁺掺杂的LaGaO₃基陶瓷的电性能的异同,并对其差异的原因进行了研究。更多还原

【Abstract】 High-temperature proton conductors have potential applications in some electrochemical devices and membrane reactors such as solid oxide fuel cells,hydrogen sensors,hydrogenation and dehydrogenation of some organic compounds,preparation by electrolyzing steam,separation and purification of hydrogen and ammonia synthesis at atmospheric pressure,etc.Ishihara discovered for the first time in 1994 that LaGaO₃ doped with Sr and Mg was a pure oxide-ionic conductor,which is considered as a promising candidate electrolyte for intermediate temperature fuel cell.However,the researches focused on its oxide-ionic conduction in the past decade.Recently,our group discovered for the first time that La_0.9Sr_0.1Ga_0.8Mg_0.2O_3-αwas a superior proton conductor in hydrogen atmosphere.But there is no report on the proton conduction in LaGaO₃ doped with Sr²⁺and Zn²⁺.In addition,there are commonly some second-phases in the LaGaO₃ based ceramics synthesized by conventional solid-state reaction method.The La_0.9Sr_0.1Ga_1-xM_xO_3-α(M = Zn²⁺,Mg²⁺)ceramics were synthesized by solid-state reaction,sol-gel and microemulsion methods,and the ionic conduction properties of the ceramics were studied by various electrochemical methods including AC-impedance,Gas concentration cell,gas electrochemical permeation under various atmospheres at 600～1000℃.The main results in the present study are organized as the following:（1）La_0.9Sr_0.1Ga_1-xM_xO_3-αceramics were synthesized through three methods,and the orthorhombic perovskite single-phase was attained by the sol-gel and microemulsion methods,which solved the problem of impurity phases in LaGaO₃-based ceramics prepared by solid-state reaction.（2）La_0.9Sr_0.1Ga_1-xZn_xO_3-αceramics were discovered to have excellent protonic conduction under hydrogen atmosphere for the first time.It is a pure proton conductor with the proton transport number t_H⁺= 1 and proton conductivityσ_H⁺（at 700～1000℃）＞10^-2 S·cm^-1under hydrogen atmosphere.（3）It was found that it is a mixed ionic conductor（proton and oxide）under wet air atmosphere for the first time.（4）It was found that it is a pure oxide ionic conductor under dry oxygen atmosphere. （5）The differences in electrical properties between Sr²⁺- and Zn²⁺- doped LaGaO₃ and Sr²⁺- and Mg²⁺- doped LaGaO₃ were compared,and the mechanism responsible for the difference was discussed.更多还原