【作者】 陈倩倩；

【导师】 章文贡；

【作者基本信息】 福建师范大学 ， 材料学， 2011， 硕士

【摘要】 采用脉冲激光轰击修饰剂气氛中固体靶的新方法,轰击YBCO固体靶连续制得原位修饰nmYBCO乙醇溶胶,探索了修饰剂的选用对nmYBCO组装形貌的影响。结果表明选用不同种类的修饰剂对nmYBCO的组装形貌有显著影响,其中以邻苯二酚和2-硝基酚修饰后的自组装形貌较为特异规整,且重现性较好。采用脉冲激光轰击2-硝基酚气氛中的YBCO靶,连续制备2-硝基酚原位修饰nmYBCO乙醇溶胶,对其结构和性质进行了表征。结果发现2-硝基酚修饰后nmYBCO出现纳米棒和纳米球形颗粒的规整形貌,晶化程度变小；样品沉积在酸处理的锌片、碱处理的铝片和锌片上时都表现出纳米微粒的自组装生长,且组装形貌规整；2-硝基酚修饰后nmYBCO的紫外-可见吸收峰发生红移,在一定程度上影响了nmYBCO的电子结构。采用脉冲激光轰击邻苯二酚气氛中的YBCO靶,连续制备邻苯二酚原位修饰nmYBCO乙醇溶胶,对其结构和性质进行了表征。结果发现邻苯二酚修饰后YBCO纳米颗粒的形貌更为规整,出现蝶状或枝状的形貌；修饰后样品沉积在未处理的铝片、酸处理和碱处理的锌片上时表现出纳米微粒的自组装生长,形貌较为规整均一；修饰后样品紫外-可见吸收峰和荧光光谱吸收峰的强度有显著降低。采用脉冲激光轰击修饰剂气氛中固体靶的方法制得原位修饰的nmYBCO固体粉末,对其进行磁性测试。结果发现未修饰nmYBCO失去了超导性,并在30.00K以下发生铁磁相变；经2-硝基酚修饰的nmYBCO在低于54.35K时恢复了超导性；经邻苯二酚修饰的nmYBCO在低于56.84K也恢复了超导性,但体系中的非超导相在26.00K时发生了铁磁相变,并且随着温度的降低,非超导相的铁磁性急剧增强,最终甚至超过了临界磁场,破坏了体系的超导性,使得nmYBCO/邻苯二酚体系失去超导性。更多还原

【Abstract】 The in-situ modified nano-YBCO ethanol sols were successively prepared by pulsed laser ablation at the interface of YBCO target in the modified atmosphere. Explored the influence on nano-YBCO assembly morphology of modifiers selection. Results showed that nano-YBCO assembly morphology had significant influence of choosing different kinds of modifiers, amomg them with pyrocatechol and 2-nitrophenol modification, the self-assembly morphology were more specific neat, and had good reproductivity.The 2-nitrophenol in-situ modified nano-YBCO ethanol sols were successively prepared by pulsed laser ablation at the interface of YBCO target in the 2-nitrophenol modified atmosphere. Their structure and properties were characterized. The results showed that after 2-nitrophenolic modification, nano-YBCO appeared neat morphology such as nano rods and nanometer spherical particles, and its crystallization degree was decrescent. While the modified samples depositing on the acid treatment zine plate, alkali treatment aluminium sheet or zine plate, they showed nanoparticles self-assembly growth, and the assembly morphology were neat. After 2-nitrophenolic modification, the nano-YBCO ultraviolet-visible absorption peaks happened redshift, the 2-nitrophenolic affected nano-YBCO electronic structure to a certain extent.The pyrocatechol in-situ modified nano-YBCO ethanol sols were successively prepared by pulsed laser ablation at the interface of YBCO target in the pyrocatechol modified atmosphere. Their structure and properties were characterized. The results showed that after pyrocatechol modification, the morphology of YBCO nanoparticles were more neat and appeared butterfly shape or branch shape. While the modified samples depositing on the untreated aluminium sheet, acid treatment or alkali treatment zine plate, they showed nanoparticles self-assembly growth, and the assembly morphology were neat and uniform. After pyrocatechol modification, the strength of nano-YBCO ultraviolet-visible absorption peaks and fluorescence spectrum absorption peaks had significantly reduced.The in-situ modified nano-YBCO powders were successively prepared by pulsed laser ablation at the interface of YBCO target in the modified atmosphere. The results of magnetic test showed that the unmodified nano-YBCO powder lost superconductivity, and hanppened ferromagnetic phase transition below 30.00K. The 2-nitrophenol modified nano-YBCO powder restored superconductivity below 54.35K. The pyrocatechol modified nano-YBCO powder also restored superconductivity below 56.84K, but non-superconducting phases of the system hanppened ferromagnetic phase transition at 26.00K. With the decrease of temperature, the non-superconducting phases ferromagnetism of the system increased sharply, eventually even more than the critical magnetic field, which destroyed superconductivity of the system, thus making nano-YBCO/pyrocatechol system lose superconductivity.更多还原