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实验用共沉淀法制备出不同铈掺杂浓度的钇铝石榴石(Y3-xAl5O12∶Cex)粉体。用综合热分析仪、X射线衍射仪、透射电镜、荧光光度计等测试手段对Y3-xAl5O12∶Cex前驱体及煅烧后的粉体进行了晶体结构、形貌和发光性能等方面的表征。研究表明:合成石榴石粉体的最佳煅烧温度应该在1050℃以上,用此方法可得到分散性好,形状规则且粒径为50 nm的石榴石粉体。随着Ce掺杂量的增加,样品的结构没有发生显著的变化,均为YAG相。只是衍射强度随着x的增加而增强。当x=0.20时,出现了CeO2相。Y3-xAl5O12∶Cex的激发光谱为双峰结构,在近紫外340 nm处有一激发峰,在可见光区有一最大激发峰在460 nm处。Ce3+的4f能级由于自旋耦合而劈裂为两个光谱支项2F7/2和2F5/2,其中2F5/2为基谱项。340 nm的激发峰对应2F5/2→5d的跃迁,460 nm的激发峰属于2F7/2→5d的跃迁。发射光谱都由一组尖峰组成,发射峰对应的波长在530 nm处。
Experimental yttrium aluminum garnet (Y3-xAl5O12: Ce) powders with different cerium doping concentrations were prepared by coprecipitation method. The crystal structure, morphology and luminescent properties of Y3-xAl5O12:Cex precursors and calcined powders were characterized by comprehensive thermal analysis, X-ray diffraction, transmission electron microscopy and fluorescence spectrophotometer. The results show that the optimum calcination temperature of synthetic garnet powder should be above 1050 ℃, and garnet powder with good dispersibility and regular shape and particle size of 50 nm can be obtained by this method. With the increase of Ce doping amount, there is no significant change in the structure of the sample, all YAG phase. Only the diffraction intensity increases with the increase of x. When x = 0.20, the CeO2 phase appears. The excitation spectrum of Y3-xAl5O12: Ce has a bimodal structure with an excitation peak at 340 nm in the near ultraviolet region and a maximum excitation peak at 460 nm in the visible region. The 4f level of Ce3 + splits into two spectral branches, 2F7 / 2 and 2F5 / 2, due to spin coupling, where 2F5 / 2 is the base spectrum term. The excitation peak at 340 nm corresponds to the transition from 2F5 / 2 → 5d, and the excitation peak at 460 nm belongs to the transition from 2F7 / 2 → 5d. Emission spectra are composed of a series of spikes, the corresponding emission peak wavelength at 530 nm.