Co吸附二氧化硅团簇的几何结构、光电及磁学特性

Structural,Photoelectric and Magnetic Characteristics of Co Adsorbed on Silica Clusters

基于密度泛函理论中的广义梯度近似方法,系统地研究了Co(SiO2)n(n=1-7)团簇的几何结构、光电特性和磁学性质。结果表明:受悬挂键和电子云分布影响,单个Co原子以一定倾角吸附在稳定性很好的(SiO2)n(n=1-7)链状团簇上,多个Co原子却在其上发生团聚作用;不断减小的垂直电离势和不断增大的电子亲和势使得Co(SiO2)n(n=1-7)团簇的硬度随着团簇尺寸的增大而降低;Co原子的吸附使得非磁性二氧化硅转化为磁性复合团簇,随着Co原子数目的增多磁矩不断增大,结合该团簇的近红外光吸收特性,从理论上证实了二氧化硅磁性复合材料既具有超顺磁性又可以吸收可见-近红外光,为其在医学界被用作光动力靶向治疗提供了理论依据。

Equilibrium geometries, photoelectric and magnetic properties of Co（SiO2）.（n=1--7） clusters have been systematically studied employing the density functional theory with a generalized gradient approximation. Owing to the effect of the dangling bonds and distribution of electron cloud, one Co atom binds to the steady and catenulate （SiO2）. （n= 1--7） clusters in nearly a fixed directiom but multi-Co atoms gather on them. The reduetiving VIP and increasing VEA caused the hardness of Co（SiO2 ）n （n= 1--7） clusters decreased with the increasing of the cluster size. The adsorption of Co atom makes the nonmagnetic silicon oxide translated into the magnetic composite clusters, and the magnetic moment increasing with the growing number of Co atoms. Combining with the near infrared absorption properties of the Co（SiO2 ）n （n= 1--7） clusters, theoretically, it was proved that the magnetic-composite silicon oxide were superparamagnetic and absorbable in the visible-near infrared light. It offers theoretical basis for photodynamic target therapy in the medical stage.