铜纳米颗粒在硅酸盐玻璃中的形成及其局部结构

FORMATION AND LOCAL STRUCTURE OF COPPER NANOPARTICLES IN SILICATE GLASS

用离子交换结合H2气氛热处理的方法制备出铜纳米颗粒/硅酸盐玻璃复合材料。利用光学吸收谱和X射线吸收精细结构谱分析了铜纳米颗粒在玻璃中的形成机理及其局部结构。结果表明:提高H2气氛处理温度有利于提高Cu纳米颗粒在玻璃中的体积分数,在其它工艺条件相同的情况下,离子交换时间从0.5h延长到1.0h对Cu纳米颗粒在玻璃中的体积分数影响不大。Cu在离子交换硅酸盐玻璃中仅存在Cu—O配位结构,热处理后铜原子在玻璃中存在2种局域结构环境:一是处于铜氧化物的配位环境;另一是处于金属铜的配位环境。玻璃中铜离子以一价存在,其周围存在2个氧配位,Cu—O键长在0.185～0.186nm之间。随着Cu颗粒尺寸的降低和Cu小分子团簇质量分数的增加,Cu—Cu配位的无序度增大。含小分子铜团簇多的样品,Cu—Cu最近邻原子间距离与铜体材料中的Cu—Cu最近邻原子间距离(0.255nm)相比发生收缩;含铜纳米颗粒较多的样品,Cu—Cu最近邻原子间距离与铜体材料中的Cu—Cu最近邻原子间距离相比发生膨胀。

Copper nanoparticle-glass composites were prepared by ion-exchange with thermal treatment in H2 atmosphere. Optical absorption spectroscopy and X-ray absorption fine structure technique were used to study the formation mechanism of Cu nanoparticles and Meal structures of copper atoms in silicate glass. Results indicate that the volume fraction ofCu nanoparticles in silicate glass increases as the annealing temperature increasing in H2. Extending the Cu^＋ for Na^＋ ion exchange duration from 0.5 to 1.0 h has little influence on the volume fraction of Cu nanoparticles. There is only Cu-O coordination structure in the ion-exchanged silicate glass, and a new Cu-Cu coordination appears after annealed in H2 atmosphere. Cu^＋ in silicate glass is coordinated by two oxygen atoms with distances ranging from 0.185 to 0.186 nm in different preparation conditions. Disorder of Cu nanoparticles increases with decreasing Cu particle size and the mass fraction of small Cu clusters in the glass. Nearest-neighbor interatomic distance of Cu-Cu coordination in glass contracts compared to bulk Cu nearest-neighbor interatomic distance when the mass fraction of small Cu clusters in the glass is large. Nearest-neighbor interatomic distance of Cu-Cu coordination in the glass expands when the mass fraction ofCu nanoparticles is large.