【作者】 曹进；

【导师】 施哲； 王达健；

【作者基本信息】 昆明理工大学 ， 有色金属冶金， 2004， 硕士

【摘要】 研究用拟薄水铝溶胶法制备稀土掺杂铝酸盐体系长余辉发光材料的工艺和机理。与固相合成法、微波合成法等相比，薄水铝石溶胶法在原料成本、工艺控制方面具有某些优点。能克服铝醇盐成本高和铝盐溶胶法杂质引入的局限性。拟薄水铝石原料溶胶法的工艺-结构-性能关系还不清楚，因此对过程相关的基础问题研究具有意义。 拟薄水铝石原料来源于中国铝业股份有限公司，铝酸盐发光材料的制备过程为：在优化的工艺条件下，通过拟薄水铝石水溶液酸度和固含量的控制，可以方便得到透明稳定的氧化铝溶胶。在拟薄水铝石溶胶中，加入纳米稀土Eu和Dy氧化物，由于稀土离子与纳米γ-A100H胶团的相互作用，能快速促进凝胶化。凝胶经过120℃干燥后脱出层间水，得到干凝胶。在自行组装的还原设备内，进行弱还原煅烧。实验表明，溶胶法得到的干凝胶形成发光相的温度得到降低。 系统地研究了拟薄水铝石溶胶法制备SrAl₂O₄：Eu²⁺，Dy³⁺发光材料的一系列工艺条件。发现不同加料方法对材料的发光性能的影响较大。根据实验结果发现，不同烧结方法对Eu²⁺形成发光中心的影响不大，而对Dy³⁺形成陷阱能级的影响较大，与其他烧结方法相比，待炉温升高后再装料最有利于Dy³⁺的引入形成合适的陷阱能级，这种加料方法不仅提高了材料的发光性能，还可达到节能的目的。 对不同恒温时间的样品进行了余辉测定，发现经过1.5小时焙烧的样品效果最好，24小时后余辉亮度仍达到0.35409mcd／m²，而烧结1小时的样品在13小时后余辉亮度已小于0.32 mcd／m²。 根据相图信息，研究了SrO—Al₂O₃，体系目标物相的形成规律。对激活剂Eu²⁺的还原机理进行了探讨，对助熔剂的作用机理进行研究，对干凝胶进行了差热差重分析，对焙烧样品进行了XRD物相分析，并对典型样品进行了余辉测定。 特别地考察了B₂O₃，对体系新生相和性能的影响规律。一般认为，助熔剂是在发光体形成过程中起着帮助融化和溶媒作用的物质，降低基质形成晶体的烧结温度和激活剂进入晶格形成发光中心及陷阱中心。在实验研究基础上，归纳出如下B₂O₃，影响规律： 1) B₂O₃的含量很小（＜2％）时，对材料的发光性能影响不大。 2) 助熔剂B₂O₃在焙烧过程与SrAl₂O₄和Dy₂O₃，发生如下反应： Dy₂O₃+SrAl₂O₄+B₂O₃=SrB₂O₄+Dy₄Al₂O₉ 昆明理工大学硕士学位论文摘要/Abstract 由于该反应的发生使得Bzo=，的含量不能过高。3)根据本实验结果，B办。在最终产品中的含量在4%左右时为最佳值 在相形成规律上，本文发现sr，A120:相容易造成srA12认:EuZ‘，Dy:“的发光碎灭现象，为了控制Sr[A1207相的生成，SrO/Al:0=;（mol）应控制在0.34附近的结论。 基于体系相形成规律和实验事实，提出了E。:t+^Eu，的弱还原还原机理的新见解。即，Eu:I+一EuZ‘的还原过程并不是还原气体的直接作用产生，而是了一离子与还原性气份反应而湮灭，释放出来的电子与E试’作用发生下列还原反应而造成的: Eu:，‘〔Xe」4f6+e一^EuZ‘[Xe〕4f下 这个电子已进入EuZ十的原子轨道中，而且Eu舒的4f处于半充满很稳定的状态，所以能量要比（Eu:，++e一）这种类H状态低。 总之，采用拟薄水铝石溶胶前驱体方法，成功制备了发光性能优异的SrA120，:EuZ‘，伪:卜长余辉光致发光材料。首次采用工业产品拟薄水铝石（pesuo boehmite）来作为原料，可实现制备成本控制;溶胶法可降低烧结温度至1200℃左右;实验全部采用无机盐原料，不采用有机物质，可避免环境污染。在实验室规模取.得的结果，可为进一步扩大规模研究和工业化提供一系列基础和工艺根据。更多还原

【Abstract】 The processes and mechanism of preparing rare earth doped strontium aluminate luminescence materials from Pseudo-boehmite sols are investigated. In comparitions of solid phase synthesis and microwave synthesis, the pseudo-boehmite sols possesses the characteristics of lower cost and easy control . Because the relationships of process - structure - property is not very clear, it is significant scientifically and technologically to the understanding the processes.The Pseudo-boehmite powders are from the China Great-wall Aluminium Industry Co.Ltd., The preparation process is described as follow: The transparent and stable aluminum oxide sol is made by way of controlling solid content and acidity under the optimized process parameters. By adding rare earths to the sols,the gel turns into xerogel by dehydrate at 120 C, The weak reduction calcination is carried out in a horenzontal furnace. The experimental result shows that the synthesis temperature is lowed.The process parameters for sol-gel route were studied systemtically.Thedifferent calcining manner has little effect on the formation of Eu2t luminescence center, but adversely on Dy’+, Fedding dry gel at the target temperature can get to a suitable trap energy level. This manner not only strengthen the luminescence capability of materials , but also energy saving.We find the optimized calcining duration is for 1. 5h by deacy curve measurements. It’ s brightness still achieves 0. 35409mcd/m" untill 24h. But the brightness of sample with Ih calcining time is smaller than 0.32 mcd/m2 after 13h.The formation of various phases during the processing is analyzed according to the phase diagram of SrO- A1A; the reduction mechanism of Eu~+ and the roles of BA are approached, The XRD patterns, DTG pattern and decay curve of as-synthesized sampleshave been measured.In particular, the role of B20:! on the phase formation is approached. It is generally believed that the flux is usually used to accelerate a solid state reaction in synthesizing long phosphorescent SrAlA: Eu2+, Dy’+ phosphor. We conclude that:(1) B203 has little effects on luminous behavior when BAi is in small amount(2) B203 will react with SrAl2O4 and Dy2O3 as follow:DyA+SrAlA+ B2O3= SrBA+ Dy4Al2O9The B203 should be controlled to small amount as the long afterglow luminous behavior is weakened with the increase of BA.(3) The optimum content of B203 in the end product is about 4% according to this experiment .It was found that SrAl2O4 : Eu2+, Dy3+ appeared luminescence quenching phenomenon when Sr,,Al207 phase formed. According to the experiment, we conclude that this phenomenon can be controlled when SrO/Al2O3(mol) is about 0.34.Baseded on the formation law of phases and experiment fact , we have a view point about the reducing process of Eu3+-Eu2+. Namely, it is not the effect of reducing gas directely, but the interaction of electron and Eu3+, then reduced. The electron comes into the atom track of Eu2+, the 4f of Eu2+ is athalf-abound, so it is very stable.In a word , the SrAl2O4: Eu2+, Dy3+phosphor with excellent physical - chemical properties has been synthesized successfully with Pseudo-boehmite sols .For the first time, the industry product (Pseudo-boehmite) has been used as primary materials, With this method , the calcining temperature can be lowred to 1200 癈. Because the primary material are all the inorganic salt, this method can avoid the pollution of the environment effectively.The laboratory-scale experimental results can provide valuable references for further scaling-up application.更多还原