Eu3+掺杂萤石矿物的发光与其晶体结构关系

对萤石矿物进行掺杂灼烧.制备了一种新型矿物发光材料萤石:Eu³⁺.根据Eu³⁺的荧光光谱与局域对称性的关系,结合空间群中等效点系的对称性分析,可以推断该体系中主要存在2类发光中心,其格位对称性分别为C_4V,和C_3V.Eu³⁺离子进入CaF₂晶格,与Ca²⁺离子不等价置换,由于电荷补偿,Eu³⁺周围常常存在间隙F_i^-的缺陷机制,间隙的存在,降低了局域对称性(由O_h降低为C_4V。或C_3V),打破了宇称选择定则,促进了Eu³⁺离子的发光.

Relationship between Luminescence and Crystal Structure of Eu3+doped Fluorite

According to the relationship between luminescent properties and local symmetry of Eu³⁺, together with the site symmetry of symmetrically equivalent points in space group, it can be inferred that there are mainly two kinds of emission centers, which have the C_4v or C_3v site symmetry respectively, in fluorite:Eu³⁺ system. The Eu³⁺ ion requires charge compensation, because it enters the cubic site in a heterovalent substitution for the Ca²⁺ ion. The charge-compensating defects, such as the predominant interstitial F_i^-, influence the local environment of the Eu³⁺ ions and, in particular, modify the site symmetry. The existence of F_i^- round the Eu³⁺ ion reduces the O_h symmetry to C_4v or C_3v, which breaks the parity selection rules and promotes the luminescence of fluorite:Eu³⁺ samples.