【摘要】 采用改进的均匀沉淀法结合固-气硫化工艺制备了一系列Y2O2S∶Yb,Ho上转换粒子.利用X射线晶体衍射(XRD)和透射电子显微镜(TEM)对粒子的结构和形貌进行了表征,并通过上转换发光光谱(UCL)和红外光谱(FTIR)研究了粒子的上转换发光性质.XRD和TEM结果表明,所制备的样品均为单一的六方相结构,且所有粒子均呈单分散和尺寸均一的球形,其尺寸分别为40,80和200nm.根据发光强度和激发功率间的对数关系曲线发现,随着粒子尺寸的降低,蓝光发射由三光子吸收过程转变为双光子吸收过程;而绿光和红光发射虽然一直保持双光子吸收过程,但其对数曲线斜率均随粒子尺寸的降低而逐渐增大.对该材料的粒子尺寸与上转换发光机制的关系进行了讨论.更多还原

【Abstract】 A series of Y2O2S ∶Yb,Ho upconversion particles were prepared using an improved homogeneous precipitation method combined with a solid-gas sulfuration technology.The structure and morphology of particles were characterized by X-ray diffraction(XRD)and transmission electron microscope(TEM),and the upconversion luminescence(UCL)properties and mechanisms were studied by UCL spectra and FT-infrared spectra(FTIR).The results of XRD indicated that the prepared samples were pure hexagonal structure.TEM images showed the prepared particles were mono-dispersed with regular sphere shape and exhibited the narrow size distribution with average size of 40,80 and 200 nm,respectively.According to the ln-ln plots of emission intensity as a function of excitation power,it was found that the blue emissions varied from three-photon absorption process to two-photon absorption process with decreasing particle size.For the green and red emissions,only the two-photon absorption process was observed,but the slope values of the lnIP-lnIUCL plot increased with decreasing particle size.The mechanism of the effects of particle size on the UCL properties was discussed.更多还原