【作者】 侯智尧；

【导师】 张密林；

【作者基本信息】 哈尔滨工程大学 ， 材料学， 2009， 博士

【摘要】 稀土元素4f电子层构型使得稀土发光材料表现出了优异的物理和化学性能,已经被广泛地应用在各种照明和显示等领域,例如荧光灯、阴极射线管、场发射显示和等离子体显示。稀土离子掺杂的光功能化的多孔材料因其独特的多孔结构和发光性质而被认为在药物传输和疾病诊断治疗等方面具有潜在的应用价值。本论文采用静电纺丝与溶胶-凝胶相结合的方法制备了稀土发光材料和光功能化的多孔材料,在样品制备、结构、形貌、光致发光性质和低压阴极射线发光性质以及药物分子储存与缓释性质等方面进行了一些探索性的研究。制备了多种形貌(纤维状、带状和管状)和尺寸不同的稀土发光材料。由于在VO43-基团与稀土离子(Ln3+)之间存在能量传递,因此紫外光激发下稀土离子在YVO4纳米纤维和微米带中呈现出它们的特征发射。用PO43-部分替代VO43-,在YP0.8V0.2O4:Ln (Ln=Eu3+, Sm3+, Dy3+)纳米纤维中,通过改变Ln3+的掺杂浓度,发光颜色可以从蓝光分别调配到红橙光、橙红光和黄绿光。在紫外光激发下,Ce3+或Tb3+单掺杂的LaPO4纳米纤维和微米带呈现各自的特征发射,即Ce3+的5d-4f跃迁和Tb3+的5D4-7FJ(J=6,5,4,3)跃迁。在LaPO4:Ce3+, Tb3+样品中,Ce3+能够向Tb3+传递能量,激发Ce3+的吸收带能够得到属于Ce3+的5d-4f发射和以Tb3+的5D4-7F5跃迁为主的绿光发射。具有白钨矿石结构的CaWO4和CaMoO4是典型的自激活荧光体,在紫外光的激发下分别发射出蓝光和蓝绿光。检测Tb3+的5D4-7F5能级,得到CaWO4:Tb3+纳米纤维和纳米管的激发光谱,与CaWO4的激发光谱相似,宽带激发归属于WO42-中配位的氧原子和中心钨原子的电荷迁移。WO42-的特征激发峰出现在Tb3+的激发光谱中说明在CaWO4:Tb3+纳米纤维和纳米管中存在从WO42-向Tb3+的能量传递。激发WO42-离子,得到相应的Tb3+f-f跃迁的发射光谱,发射光谱中以5D4-7F5能级的绿光发射最为显著。与Tb3+离子的特征发射相比,CaWO4:Tb3+纳米纤维和纳米管中来自WO42-内在的蓝光发射是很微弱的,这表明在WO42-与Tb3+之间的能量传递是显著有效的。在CaMoO4:Ln (Ln=Eu3+, Tb3+, Dy3+)纳米纤维中,同样存在MoO42-向Ln3+的能量传递,通过改变Ln3+的掺杂浓度,可以将发光颜色从蓝绿光分别调配到红橙光、绿光和黄光。Gd2MoO6:Eu3+纳米纤维和纳米带的发射光谱对应于Eu3+的f-f跃迁,并且以Eu3+的5D0-7F2超灵敏跃迁红光发射为主。在Eu3+的激发光谱中出现了归属于Gd2MoO6强吸收峰,说明发生了从MoO66-向Eu3+的能量传递。在紫外光和低压阴极射线的激发下,制备的稀土发光材料都能够呈现掺杂稀土离子的特征发射。尺寸稍大的带状和管状荧光粉的晶体缺陷少,使得它们的发光强度大于纤维状的荧光粉。利用静电纺丝法制备的多种稀土发光材料在不同的彩色显示领域具有潜在的应用价值。以阳离子表面活性剂作为模板,制备了光功能化的多孔Eu3+掺杂的羟基磷灰石(HAp)纳米纤维和微米带。以布洛芬(IBU)作为模型药物,研究了HAp:Eu3+光功能化多孔材料作为药物载体在模拟体液中药物储存/释放性质。研究结果表明,该体系对IBU具有一定的药物缓释性能,且发光强度会随着药物释放量的增加而逐渐恢复到载药前的水平。作为一种新的药物释放体系,具有多孔结构和荧光性质的HAp:Eu3+;纳米纤维和微米带在药物控/释以及疾病诊疗等领域表现出潜在的应用前景。更多还原

【Abstract】 Rare earth luminescent materials have been widely used in the fields of lighting and display, such as fluorescent lamps, cathode-ray tubes, field emission displays and plasma display panels, and other functional materials based on their outstanding physical and chemical properties arising from their 4f electrons. It is worth noting that porous materials functionalized with photoluminescence via doping rare earth ions have potential applications in the fields of drug delivery and disease diagnosis and therapy. In this dissertation, valuable explorations have been carried out on a combinative synthetic method of electrospinning and sol-gel process to rare earth oxides luminescent materials and luminescence functional porous materials, as well as their preparation, structure, morphologies, photoluminescent, cathodoluminescent and drug delivery properties.A series of rare earth oxides luminescent materials with different morphologies (fiber-like, belt-like and tube-like) and sizes have been prepared. Due to the efficient energy transfer from the VO43- group to the lanthanide ions (Ln3+), the Ln3+ show their characteristic strong emissions in the YVO4 nanofibers and microbelts under ultraviolet excitation. With PO43- ions partial replacement of the VO43- ions, multicolor tuning emissions of the YPo.8Vo.204:Ln nanofibers can be achieved by changing the doping concentration of Ln3+. Under ultraviolet excitation Ce3+ or Tb3+ doped LaPO4 nanofibers and microbelts show their characteristic emission, i.e. Ce3+ 5d-4f and Tb3+5D4-7FJ (J= 6,5,4,3) transitions, respectively. Excitation into the Ce+ band yields both the weak emission of Ce3+ and the strong emission of Tb3+(5D4-7FJ, J= 3,4,5,6) in Ce3+and Tb3+codoped LaPO4. This indicates that an energy transfer from Ce3+ to Tb3+occurs in the nanofibers and microbelts of LaPO4.As self-activating phosphors, calcium tungstate (CaW04) and calcium molybdate (CaMoO4) with the scheelite structure, can exhibit blue and blue-green emission, respectively. The excitation spectrum of CaWO4:Tb3+ nanofibers or nanotubes consist of a broad band due to charge transfer absorption from the oxygen ligands to the central tungsten atom within the WO42- groups. The presence of the excitation peak of WO42- groups in the excitation spectrum of Tb3+indicates that there is an energy transfer from the WO42- groups to Tb3+ ions in the CaWO4:Tb3+nanofibers and nanotubes. Excitation into the WO42- group yields the emissions spectrum corresponding to the f-f transitions of Tb3+, which is dominated by the green emission 5D4-7F5 transition. Compared with the emission of Tb3+, the intrinsic blue emission from WO42- groups is very weak, suggesting that an efficient energy transfer from WO42- groups to Tb3+ has occurred. The energy transfer process also occurs between MoO42-and Ln3+in CaMoO4:Ln (Ln= Eu3+, Tb3+, Dy3+), the corresponding luminescence color can be tuned from blue-green to green, yellow, orange-red by changing the doping ion (Ln3+) and the doping concentrations of Ln3+ion in CaMoO4 nanofibers. Excitation into the host band of Gd2MoO6:Eu3+ nanofibers or nanobelts yields the emission spectrum corresponding to f-f transitions of Eu3+, which is dominated by the hypersensitive red emission 5Do-7F2 transition. The presence of the strong host band in the excitation spectrum of Eu3+ indicates that there exists an energy transfer from Gd2MoO6 host to the doped Eu3+Under ultraviolet excitation and low-voltage electron beam excitation, the doped rare earth ions show their characteristic emission in the obtained rare earth luminescent materials. The belt-like and tube-like phosphors have higher luminescence intensity than fiber-like phosphors due to lower defect concentration in the former. These studies indicate that electrospinning is a facile route for the development luminescent materials that are useful in many types of color display fields. Luminescent, porous and bioactive europium-doped hydroxyapatite (HAp:Eu3+) nanofibers and microbelts have been prepared by a combination method of sol-gel and electrospinning process using cationic surfactant as template. The obtained multifunctional hydroxyapatite nanofibers or microbelts, which possess porous structure and red luminescence property, can be performed as a drug delivery host carrier to investigate the drug storage/release properties using ibuprofen (IBU) as a model drug. In addition, the emission intensity of Eu3+ in the drug carrier system varies with the released amount of IBU, thus making the drug release be easily tracked and monitored by the change of the luminescence intensity. This material, which combines the porous structure and the strong red luminescent property, can be served as a novel functional drug delivery system, demonstrating a great potential in the drug delivery and disease therapy field.更多还原