【作者】 姜玉玲；

【导师】 朱少敏；

【作者基本信息】 大连交通大学 ， 环境科学， 2010， 硕士

【摘要】 首次采用离子交换低温水热法合成了不同粒径及不同形貌的氧化铈前体。经过离子交换纤维的预交换度、尿素浓度、合成温度、合成时间等因素的调变可获得不同粒径分布的以纳米片和微米棒为特征形貌的氧化铈前体。较小粒径的氧化铈前体可以通过适当降低离子交换纤维的预交换度和适度提高反应温度而获得；一定粒度微米棒组合成的花状团簇结构可通过特征实验条件的控制获得。离子交换低温水热法中离子交换纤维的加入对棒状结构氧化铈前体的形成和生长具有导向作用。沉淀剂尿素的用量、离子交换纤维的预交换度、合成温度、合成时间对产物形貌和粒度的影响是通过影响离子交换纤维表面Ce(OH)2+基团和CO32-离子的扩散和迁移能力实现的。离子交换低温水热法合成的氧化铈前体为斜方结构的Ce2O(CO3)2·H20单晶,TG结果显示,离子交换低温水热法合成的氧化铈前体中已经有大量氧化铈生成,其可能以无定型状态高分散于Ce2O(CO3)2·H20晶体中。合成的氧化铈前体经400-500℃焙烧后可得到立方多晶结构的CeO2,其结晶良好,并能够保持前体的基本形貌特征。离子交换水热法中晶粒的形成、生长速度与预交换度、尿素的浓度、温度等条件有关,离子交换纤维在一定条件下成为晶粒生长的模板,控制成核和生长过程,实现了低温双控合成不同形貌纳米材料：体系中的杂质离子通过交换反应在离子交换纤维上富集,无需对产品进行洗涤。整个合成过程节能并环境友好,为高纯纳米材料的合成开辟了一条新途径。更多还原

【Abstract】 In this paper, different morphology and different partical size of precursors of cerium oxide were synthesized for the first time by low-temperature hydrothermal and ion exchange method. After modulating factors of the ion exchange fiber pre-exchange degrees, the concentration of urea, synthesis temperature and time, cerium oxide precursors with different particle size distribution and nanometer slice and micron stick for feature morphology were obtained. Smaller diameter of cerium oxide precursor can obtain by appropriately reducing pre-exchange degree of ion exchange fiber and moderately increasing reaction temperature; certain particle size of flower shape clusters self-assembly by micron sticks can be obtained under the feature synthesized condition.Additive ion exchange fiber plays the leading role in the formation and growth of rodlike cerium oxide precursor in ion exchange and low-temperature hydrothermal method. The influence of the amount of urea, the ion exchange fiber pre-exchange degrees, synthesis temperature and synthesis time on the morphology and size of product realized by affecting the capacity of diffusion and migration of Ce(OH)2+ and CO32- on the surface of ion exchange fiber.The cerium oxide precursor prepared by ion-exchange and low-temperature hydrothermal is orthorhombic structure mono-crystal Ce2O(CO3)2·H2O, according to the results of TG, abundant cerium oxide consist in cerium oxide precursor, which probable highly dispersed in Ce2O(CO3)2·H2O crystal with no finalize the design condition, after roasting at 400 to 500℃obtained cubic pleomorphic CeO2, well crystallization, and can keep the basic morphological features of precursor.The formation and growth rate of grains prepared by ion-exchange hydrothermal method are related to the pre-exchange degrees, the concentration of urea, the temperature conditions, ion exchange fiber become grain growth template under certain conditions, controlling the nucleation and growth process, realized synthesizing different morphology nanomaterials at the low-temperature dual control; impurity ions of system enriched in fiber through ion exchange reaction and have no need to wash. The whole synthesis process is environment friendly and energy saving, opening a new way for the synthesis of high purity of nanomaterials.更多还原