碳酸氢铵共沉淀法制备Gd2O3:Eu纳米晶及其性质研究

以硝酸稀土为原料,碳酸氢铵作沉淀剂,PVA为分散剂,通过控制一定的反应条件,制得易沉降、过滤的碳酸钆(铕),此前驱物在一定温度下焙烧即可得到Gd2O3:Eu纳米晶.通过红外光谱、差热-热重、X射线衍射、扫描电镜等多种分析测试方法,研究了碳酸钆(铕)的组成、分解过程,以及Gd2O3:Eu的形成过程、微观形貌和粒度.结果表明:前驱物碳酸钆(铕)在较低的温度(700 ℃)焙烧即可制得Gd2O3:Eu纳米晶的纯相,属立方晶系,颗粒呈球形.当焙烧温度从700 ℃升高到1 000 ℃时,粒径从约50 nm增大到70 nm.对样品的激发光谱、发射光谱测定表明:Gd2O3:Eu纳米晶在265 nm光激发下,发红光,发射光谱谱峰在611 nm;与体材料相比,激发光谱中电荷迁移带(CTB)明显红移,从体材料的255 nm移至265 nm.

Preparation and Properties of Gd2O3:Eu Nanocrystalline by Co-precipitation Method Using NH4HCO3 as Precipitator

Using gadolinium and europium nitrate as raw materials, NH_4HCO_3 as precipitator and PVA as dispertant, Gd_2O_3:Eu nanocrystalline was prepared. The composition and heat decomposition mechanism of gadolinium (europium) carbonate precursor, the formation process of Gd_2O_3:Eu and the micrograph of the particles were investigated by IR, TG DTA, XRD, SEM. The results show that pure cubic phase Gd_2O_3:Eu nanocrystalline has been produced by the gadolinium (europium) carbonate calcinated at 700 ℃ for 2 h. The nanoparticles of the Gd_2O_3:Eu are basically spherical in shape. The grain size increases from about 50 nm to (70 nm) when the calcination temperature increases from 700 to 1 000 ℃. The luminescent properties of phosphor were analyzed by measuring the excitation and emission spectrum. The main emission peak of the sample is at 611 nm, resulting in a red emission. Compared with micron scale Gd_2O_3:Eu phosphors prepared by a conventional method, a clear red shift occurs in the excitation spectrum of Gd_2O_3:Eu nanocrystalline prepared by the present work, from 255 nm for the conventional one to 265 nm.