【作者】 李小女；

【导师】 梅炳初；

【作者基本信息】 武汉理工大学 ， 材料学， 2012， 硕士

【摘要】 针对单晶和玻璃作为固体激光介质材料的一些缺点,本文拟制备一种新型的激光工作物质—多晶透明陶瓷。随着纳米粉体制备技术和高真空热压烧结工艺的发展,Re:CaF2透明陶瓷因具有优异的光学性能、热机械性能和稳定的物化性质,有望取代Re:CaF2单晶,引起了广大专家学者的极大关注。相对于其他稀土离子,Er3+离子具有丰富的能级结构,其某些激光波段,在高浓度掺杂下存在交叉驰豫现象,特别适合激光泵浦,是一种具有广阔应用前景的上转换材料；另外,Er3+掺杂的激光材料在处于人眼安全范围的1.5μm和2.9μm两个波段均具有发光通道,该波段的激光可以非常广泛地应用于光通信、医疗、激光探测和测距等领域。Er3+:CaF2透明陶瓷中Er3+离子较易形成团簇结构,团簇结构中的Er3+离子对会产生强烈的荧光猝灭效应,本文拟在Er3+:CaF2透明陶瓷中掺入Na+离子阻止Er3+离子的团簇结构形成,提高荧光量子效率。本论文首先采用直接沉淀法制备掺铒氟化钙纳米粉体,通过X射线衍射仪、场发射扫描电镜、透射电镜、分光光度计和电感耦合等离子发射光谱仪等分析手段研究不同的反应溶液浓度对Er3+:CaF2纳米粉体结构、形貌、粒径和稀土真实掺入量的影响。结果表明,随着反应溶液浓度的增大,粉体晶粒尺寸逐渐减小,团聚程度加剧,稀土离子的真实掺入量逐渐减少。反应溶液浓度为C1时合成粉体分散性最好,颗粒平均尺寸约为32nm,有利于制备性能优异的Er3+:CaF2透明陶瓷。在978nm LD泵浦下,该粉体实现了绿色(530-550nm)和红色(650-660nm)两种上转换发光,与之对应的Er3+辐射跃迁分别属于2H11/2,4S3/2→4I15/2和4F9/2→4I15/2,相对绿光而言红光发射强度较强。将合成的Er3+:CaF2纳米粉体和NaF粉末于酒精中充分混合均匀、干燥后,采用真空热压烧结技术制备Er3+, Na+:CaF2透明陶瓷,研究不同的烧结温度、保温时间、压力等对陶瓷致密化过程和微观结构的影响。结果表明,烧结温度T4、压力P2、保温时间t3制备的陶瓷在紫外-近红外波段的最大透过率为85.096%。系统研究Na+离子对透明陶瓷微观结构、化学组成及光学性能的影响。结果表明,共掺Na+离子减少了杂质CaO和Er2O3的含量；Na+离子有效阻止Er3+离子团簇,增加荧光量子效率,提高荧光寿命,同时引入了一种新的对称格位Er3+-Na+离子对,导致吸收峰和发射峰强度逐渐降低,峰型变窄；Na+离子过量时Er3+主要以Er3+-Na+形式存在,Er3+-Na+的跃迁振子强度低于Er3+-Fi-,从而减小Er3+离子跃迁概率,荧光寿命降低。更多还原

【Abstract】 Based on some shortcomings of single crystal and glasses as a solid laser medium material, transparent polycrystalline ceramic were synthesized to provide a novel laser material, with using nano-crystal technology and hot-press vacuum sintering method. The transparent CaF2ceramic co-doped with Re ions have attracted great intresent and have become a research focus, which is a promising material as a great substitute to CaF2single crystal because of its good optical properties, thermo-mechanical performance, stable physical and chemical nature. As one of the most popular and efficient rare-earth ions, erbium ion (Er3+) has attracted great interests because it emit in1.5um and2.9um optical communication windows. These lasers have been widely used in the field of optical communications, medical and laser detection. Besides, the Er3+ion can efficiently emit photons in the blue, green, and red regions of the spectrum and has the ability to convert infrared light to visible. However, clusters structure of Er3+can form easily and result in fluorescence quenching when with high concentration of Er3+in CaF2matrix. Thus, in this paper, Na+was co-doped with Er3+as a charge compensator in CaF2transparent ceramic in order to decrease the amount of clusters structures of Er3+and increase the fluorescence lifetime.The erbium doped calcium fluoride nanopowders were prepared by direct precipitation method. The influence of solution concentration on morphology, particle size and rare earth ions doping amounts actually of Er3+:CaF2nanopowders were investigated by XRD, FE-SEM, TEM, ICP and spectrophotometer methods. The results show that along with the increase of the solution concentration, powder particles size decreases, and reunion aggravates, rare earth ions doping amounts actually reduce. When the concentration of solution is C1, the powder is well dispersed, particle size is32nm on average, which is favorable for good sinterability of Er3+:CaF2ceramics. Upconversion luminescence of green(530-550nm) and red(650-660nm) was observed under the excitation of978nm, which is due to the transition of2H11/2,4S3/2→4I15/2,4F9/2→4I15/2, respectively, and the intensity of green emission at550nm is relative weaker than that of the red emission at660nm. Er3+, Na+:CaF2transparent ceramics were fabricated by HP method, The mixture of Er3+:CaF2nanopowder and NaF powder were used as starting materials. Effects of sintering temperature, pressure and holding time on the properties of the ceramics have been discussed. The results showed that the transmittance of Er3+, Na+:CaF2transparent ceramics was sintered at T4, P2for t3under a vacuum was85.096%from the VUV to the IR.Effects of Na+ion on structure, chemical composition and optical properties of transparent ceramic were investigated. The results showed that co-doped Na+ion reduce the impurities of CaO and of Er2O3and prevent the Er3+ion clusters effectively, improve the fluorescence lifetime. One certain site of Er3+ions (Er3+-Na+) should form in Er3+, Na+:CaF2transparent ceramic, and it should be predominant with increasing Na+concentration, leading to the narrowed and deformed absorption and emission bands. Transition oscillator strength of Er3+-Na+is weaker than that of Er3+-F-, leading to decreased absorption and infrared emission and up conversion emission intensity.更多还原