掺三价铈离子四偏磷酸盐NaLn(PO3)4(Ln=La，Gd)的真空紫外光谱研究

VUV Optical Properties of Ce^(3+) Doped NaLn(PO_3)_4(Ln=La,Gd)

用高温固相法合成了NaLn(PO3)4∶1.0%(原子分数)Ce3+(Ln=La,Gd)两种粉末发光材料,在合肥国家同步辐射实验室(NSRL)测得两种样品中Ce3+的真空紫外光谱。根据真空紫外光谱图,得到了两种稀土偏磷酸盐中所掺Ce3+离子5d轨道的能级分裂图。结合NaLa(PO3)4和NaGd(PO3)4的单晶结构数据,发现随着Ln-O平均键长的减小,Ce3+离子5d轨道的晶场劈裂(εcfs)、重心位移(εc)和总的红移(total red-shift,D)均增大。根据配体极化模型,计算了两种化合物中掺杂Ce3+离子的有效平均键长(Reff)和光谱极化率(αsp),发现随着平均键长Rav(Ln-O)变短,Ce3+离子的光谱极化率(αsp)也随之减小。

Two powder samples NaLn （PO3）4 ： 1. 0at % Ce^3＋ （Ln = La, Gd） were synthesized by the solid- state reaction method. The VUV luminescence spectra at room temperature were measured at NSRL. On the basis of VUV excitation spectra of Ce^3＋ ions in both samples, the energy level diagram of Ce^3＋ ions was proposed. Combined the VUV excitation spectra of Ce^3＋ and the structural parameters of NaLn （PO3）4 （Ln = La, Gd） single crystals, it was found that thetotal total bond crystal field splitting （ εefs）, centroid shift （ ε e）, redshift D （A） increased as the average Ln - O lengths [Rav（Ln - O）] became shorter. According to the ligand polarization model, the effective average Ce- O bond length （Reff） and the spectroscopic polarizability （αsp） were also calculated. And it was obtained that the spectroscopic polarizability （α sp） decreased when the Ray （Ln - O） shortened.