晶粒尺寸调控Er^(3+)掺杂微晶玻璃上转换发光颜色的研究

Adjusting Upconversion Luminous Color of Glass Ceramic with Er^(3+) Doped by Changing the Size of Crystals

首先,使用高温熔融冷却技术,制备了不同掺入比例的NaF,YF_3玻璃样品。然后将退火后的玻璃样品切割加工成15mm×15mm×3mm,实施抛光处理。最后,通过差热分析确定玻璃转变温度Tg、第一析晶峰Tx和玻璃整体析晶峰Tc等特征温度。将样品在600℃下热处理2h后,在玻璃样品中成功的析出了不同晶粒尺寸的NaYF4微晶。对样品进行了XRD,TEM和EDX的分析,可以确定不同样品中晶粒的尺寸与分布。结合样品荧光光谱和吸收光谱的分析,探讨了Er^(3+)在不同晶粒尺寸样品中的上转换发光特征,当晶粒尺寸由大变小时,Er^(3+)逐渐由红光发射转向绿光发射。通过析晶活化能的分析,确定了NaF可以改善玻璃网络结构,当NaF含量降低时,可以提高玻璃网络结构的完整性,增加玻璃样品的析晶活化能,降低了微晶玻璃样品的析晶能力,进而对微晶玻璃样品内微晶尺寸起到调节作用。因此:当样品中NaF含量较高时,晶粒尺寸较大,晶粒中的Er^(3+)浓度较高,使得Er^(3+)-Er^(3+)之间的交叉驰豫作用增强,导致Er^(3+)红光发射较强;相对应地,NaF含量较低时,晶粒尺寸较小,晶粒中Er^(3+)浓度较低及交叉弛豫减弱,因此,Er^(3+)绿光发射增强。通过改变玻璃组分,调节微晶玻璃中晶粒尺寸,实现了对Er^(3+)在微晶玻璃中发光颜色的调控。

Er3＋ ion doped glass samples with different doping ratio of NaF and YF3 were prepared with traditional melt cooling technology and all samples were cut into small piece of about 15 mm×15 mm×3 mm for polishing process. The glass transition temperature （Tg） and obvious crystallization peaks were determined by differential thermal analysis. The glass samples were heated at 600 ℃ for 2 h. After the thermal treatment, some intensity diffraction peaks correspond to cubic NaYF4 nanocrystals with different size. The size and distribution of the crystallites were determined by XRD，TEM and EDX analysis of glass ceramic samples. From fluorescence spectra and absorption spectra of glass ceramic samples, the color was changed. In the result of crystallization activation energy, it can be determined that glass network structure can be influence by NaF. When the content of NaF is low, integrity of glass network structure is high, and the crystallization activation energy of glass is increased. So the crystallization ability of glass is reduced. From the result of experiments, when the content of NaF is higher, the size of crystals is bigger, the concentration of Er3＋ ions in the crystal is higher. And the same time the phenomenon of cross relaxation between Er3＋ and Er3＋ will be enhanced. It will be caused red emission of Er3＋ stronger. Correspondingly, When the content of NaF is reduced, the size of crystals is smaller, the concentration of Er3＋ ions in the crystal is lesser. the phenomenon of cross relaxation between Er3＋ and Er3＋ will be weakened. At this time, the sample will realize green emission. In this paper, the luminous of glass ceramic with Er3＋ doped is adjusted successfully by changing the size of crystals.