【作者】 王静慧；

【导师】 宁桂玲；

【作者基本信息】 大连理工大学 ， 化学工艺， 2010， 博士

【摘要】 镁铝醇盐是合成铝酸镁(MgO·nAl2O3)基材料的重要前驱体之一,MgO·nAl2O3基材料作为节能照明及显示领域中重要的支撑材料而备受研究者的关注。对于此类材料来说,极少量铁族元素杂质存在可严重影响其品质。同时器件制备技术的飞速发展对MgO·nAl2O3基荧光体的性能要求也更为严格,传统的制备工艺合成的产物存在团聚严重、产物形貌无规及热稳定性差等尚未解决的问题,使其已不能满足要求。因此开展异丙醇铝镁前驱体的合成及纯化,研究不同MgO·nAl2O3基荧光体的制备及其发光特性,对于MgO·nAl2O3基材料的基础研究和应用领域拓展都有着十分重要的意义。本论文以探索不同类型MgO·nAl2O3基荧光体及发展相关制备方法为目的,研究了异丙醇铝镁前驱体的控制合成及纯化；研究了不同镁铝比的荧光体制备及其发光特性；并考察了制备方法、反应参数等对产物形貌、发光强度及稳定性的影响,主要内容和结果如下：1.采用添加剂缓蚀保护的方法合成高纯异丙醇铝镁。以镁与异丙醇铝为原料制备不同镁铝比的醇盐,讨论了各种类型添加剂对铁杂质去除的影响,研究了添加剂的加入量及反应时间对杂质含量影响。实验结果表明添加NP,可以使减压蒸馏后的醇盐中铁含量降低到5 ppm以下,满足了荧光粉对原料纯度的要求。2.采用改进的湿化学法合成MMgAl10O17：Eu2+(M=Ba,Sr)超细准球形荧光体。以高纯异丙醇铝镁为原料,利用醇盐水解形成金属-氧网络结构特性,制备了具有核-壳结构的前驱物,着重研究了水解条件对产物形貌及发光性质的影响。采用XRD、TG-DTG、SEM、TEM及PL等方法对产物进行表征。结果发现,核-壳结构通过限制扩散反应提高了荧光体颗粒的分散性,可有效的改善高温焙烧过程因自身晶向生长特性导致的形貌无规、颗粒团聚等问题。同时紫外激发下,Zn／B共掺杂具有良好的协同作用,能够大幅提高荧光体的发射强度,为改善其他相关荧光体的发光性能提供了新的选择。3.探索了球形MgAl2O4：Eu2+及其有机-无机复合荧光体的发光特性。以葡萄糖水热条件下脱水聚合生成的含碳有机物为模板,制备了球形MgAl2O4：Ln(Ln=Eu3+,Tb3+)荧光体,探讨了反应物配比、阴离子等对产物形貌的影响,重点研究了8-羟基喹啉铝-MgAl2O4：Eu3+有机-无机复合荧光体的发光性质。采用XRD、SEM、EDS、TEM、FT-IR及PL等对产物进行表征。结果表明,镁铝配比的调变可以在一定程度上调节产物的粒径,球形形貌能够显著改善荧光粉的发射强度；将8-羟基喹啉铝引入到空心微球的孔道中,合成了有机-无机复合发光材料,调节8-羟基喹啉铝与MgAl2O4：Eu3+的比例,实现了产物发光在绿光-黄光-红光范围的调变。4.进一步探讨了形貌控制对镁铝复合氢氧化物异质结构发光性质的影响。在乙二胺辅助水热条件下合成了不同形貌的镁铝复合氢氧化物Mg2Al(OH)6(C03)0.5·H2O1.5(LDH)/AlOOH异质结构。实验详细考察了反应温度、添加剂、初始pH值及反应时间对产物形貌的影响,并探讨了异质结构可能的生长机理。采用XRD、TG-DTG、SEM、TEM、SAED、FT-IR及PL等方法对产物进行分析表征。实验结果表明,高温有利于片状单元组装反应进行,乙二胺有助于片层基元的稳定,制备的玫瑰花状异质结构使产物具有特殊的发光性质,随着激发紫外光波长的不断增大,其发射光谱在蓝光波段的峰位也呈现出相应的红移变化。更多还原

【Abstract】 As good candidates for full color emitters, aluminate-based phosphors have drawn extensive attention, especially for their application in plasma display panels. Magnesium aluminum isopropoxide is widely employed in the preparation of aluminate-based advanced materials. Among the physical and chemical properties, purity of raw materials plays a vital role. It is necessary to guarantee quality by controlling the content of contaminants. Trace of iron impurity could cause severe quenching of luminescence. Thus, it is necessary to remove iron from magnesium aluminum isopropoxide. In addition, the products derived from traditional synthetical methods usually suffer from several problems. The main points lie in its unstability that caused either by impurity in raw material or heat-resistance and aggregation that is brought by traditional solid-state reaction. Therefore it is urgent to find new synthetic methods and alternative luminescent materials with appropriate raw material that is accessible and high purity. In the present work, we focus our attention on the synthesis and purification of magnesium aluminum isopropoxide, development in synthetic method of aluminate-based phosphor and improvement in luminescent properties and morphological control of the aluminate phosphor. The results are given as follows:1. Different synthetic procedures have been considered. A one-pot two-step reaction route was chosen to synthesize alkoxide with different ratio of Mg/Al. A facile and effective method has been employed to remove the trace iron impurity in magnesium aluminum isopropoxide. Effective prevention of iron from its reaction with isopropanol or isopropoxide is generated by adding NP. Thus the iron content can be reduced from more than 20 ppm to less than 5 ppm in the resulting products.2. Different wet chemical methods are applied to improve the performance of aluminate-based phosphors. Barium or strontium magnesium aluminate obtained from a nano-coating route showed higher intensity compared with those from traditional solid-state reaction. The precursor had core-shell structure so that the reaction of the materials could be confined in the given field. Therefore hexagonal plate-like crystallization can be inhabited, resulting in quasi-spherical fine products. As for the SAM sample prepared by hydrocarbonate-gel method, photoluminescence intensity could be enhanced by co-doping of Zn and B. XRD patterns revealed that the sample that had the highest intensity also displayed the best crystallinity. The reason may lie in the improvement of host cell parameters by bigger Zn2+cation with the combination of flux.3. MgAl2O4:Ln (Ln=Eu3+, Tb3+) hollow microspheres have been obtained through hydro-thermal treatment and further calcination process. The resulting products have good dispersity with diameter in the range of 1～2.5μm. On changing the Mg/Al ratio, particle size and thickness of the shell were controlled to some extent. Energy transfer was observed from Tb3+ to Eu3+by simply regulating the molar ratio of Eu/Tb. Inorganic and organic luminescent complex could also be obtained by introducing Alq3 in the mesoporous MgAl2O4:Eu3+ and tunable emission from green to red can also be achieved by changing the ratio of the two components.4. Magnesium aluminum hydroxide complex with different morphologies have been synthesized. Uniform 3D rosette-like Tb3+-doped LDH/AlOOH heterophasic architectures assembled from nanosheets building blocks were successfully prepared via ethylenediamine-assisted hydrothermal method for the first time. It was found that ethylenediamine was crucial to the rosette-like architectures, in which each microflower was assembled by layer-by-layer growth of homocentric superposed nanosheets. It could also be concluded that high reaction temperature was in favor of assembly of the nanosheets building units. Photoluminescence measurements indicated that products possess multiple and tunable emissions in the blue region under different ultraviolet light excitation.更多还原