柠檬酸的用量在溶胶凝胶燃烧合成法中对Y_2O_3:Er发光性能的影响

Effects of Dosage of Citric Acid on Up-Conversion Luminescent Properties of Y_2O_3:Er in Nitrate-Citric Acid Sol-Gel Combustion Synthesis

采用硝酸盐-柠檬酸溶胶凝胶燃烧合成法制备了Er3+掺杂Y2O3上转换发光粉体,研究了不同柠檬酸用量对Y2O3:Er粉体晶体结构、颗粒形貌、颗粒尺寸和上转换发光性能的影响。研究结果表明,柠檬酸加入量的多少不会影响粉体的晶体结构,XRD图谱的衍射峰位置没有发生改变;只是随着柠檬酸的增加,可能会导致晶粒发育不完全,使得参加衍射的晶胞数变少,衍射峰发生明显的宽化。不同柠檬酸加入量下得到的粉体,颗粒尺寸都在纳米级;随着柠檬酸加入量的增加,颗粒尺寸变小,表面能增加,团聚更明显。柠檬酸加入量对发光性能影响较为明显,当柠檬酸与硝酸盐的摩尔比为2时,4S3/2/2H11/2→4I15/2跃迁所对应的绿光发射强度和4F9/2→4I15/2跃迁所对应的红光发射强度都呈现出了最大值。这是因为体猝灭中心与表面猝灭中心对Er3+离子的上转换发光猝灭作用都处于一个相对较弱的状态,同时由于C3 i格位上的Er3+离子的电偶极跃迁的宇称禁戒解除,使得C3 i格位上的Er3+离子的发射增强,这就使得粉体的上转换发光整体增强,并达到最大值。

Y2O3 powders doped with Er3+ were synthesized by nitrate-citric acid sol-gel combustion synthesis.Effects of usage of citric acid on the crystal structure,particle morphology,particle size and up-conversion luminescent properties of Y2O3:Er were investigated.It was exhibited that the amount of citric acid did not affect the crystal structure of Y2O3.There was no change in the positions of diffraction peaks in the XRD pattens.The increase of citric acid might result in that grain growth was not complete,making the cell number fewer to participate in diffraction and diffraction peaks of significant broadening.Particle size was in nano-scale by adding different amount of citric acid.With the amount of citric acid dereased,particle size was smaller,surface energy increased and the particle reunited more obviously.Citric acid addition affected the luminescence properties greatly.When the molar ratio of citric acid and nitrate was 2,green light emission intensity corresponding to 4S3/2/2H11/2→4I15/2 transition and the red emission intensity corresponding to 4F9/2→4I15/2 emerged the maximum value.Effects of body quenching center and surface quenching center on the upconversion luminescence quenching of Er3+ ion was relatively weak.Moreover,parity-forbidden transition of electric dipole transition of Er3+ ion on the C3i position was released,enabling the emission of Er3+ ion on the C3i position increased,which both made the whole up-conversion luminescence increased,and to the maximum.