Eu^(2+)在多相体系中的发光

The Luminescence of Eu 2+ in Mixed Phase System

研究了基质结构与离子半径的形成关系和Ｅｕ２＋在同时形成的多相体系中的发光现象．在ＭＭｇＡｌ１０Ｏ１７体系中，当Ｍ离子半径小于０．１０ｎｍ时，体系形成多相共存．首次观察到在磁铅矿、尖晶石和α－Ａｌ２Ｏ３三相同时共存体系中，Ｅｕ２＋优先占据离子半径和电荷与之匹配的磁铅矿中的Ｃａ２＋离子格位，不进入尖晶石和α－Ａｌ２Ｏ３晶相中的Ｍｇ２＋、Ａｌ３＋离子格位，仅产生Ｅｕ２＋的ｄ→ｆ跃迁宽带发射，且观察不到Ｅｕ３＋的特征光谱；在尖晶石和α－Ａｌ２Ｏ３两相同时共存体系中，Ｅｕ２＋可进入尖晶石和α－Ａｌ２Ｏ３晶相中的Ｍｇ２＋、Ａｌ３＋离子格位，分别产生Ｅｕ２＋的ｄ→ｆ和ｆ→ｆ跃迁发射，同时还观察到相当强的Ｅｕ３＋的特征光谱；在α－Ａｌ２Ｏ３单一相中，Ｅｕ２＋产生ｆ→ｆ跃迁发射，并观察到明显的Ｅｕ３＋的特征光谱，在α－Ａｌ２Ｏ３与γ－Ａｌ２Ｏ３同时存在的混合相中，Ｅｕ２＋的ｆ→ｆ跃迁发射消失。

The dependence of the structure of the hosts on the M ion radius in MMgAl 10 O 17 (M=Be, Mg, Ca, Sr, Ba, Pb, Eu, Mn, Fe, Co, Ni, Zn, Cd, Sn) system was studied and the luminescence of Eu 2+ in the mixed phase system was discussed. When M ion radius is less than 0.10 nm, the system MMgAl 10 O 17 constructs by the mixed phases consisting of manegtoplumbite and spinel, α alumina or spinel and α alumina. In the mixed phase of manegtoplumbite and spinel and α alumina, Eu 2+ ion preferentially occupies lattice site of the cations in manegtoplumbite well matched with the radius and charge of Eu 2+ . There exists only d→f transition emission of Eu 2+ and no characteristic emission of Eu 3+ occurs in those hosts. In the mixed phase of spinel and α alumina, Eu 2+ can enter the lattice site of Mg 2+ ion or Al 3+ ion and the d→f and f→f transition of Eu 2+ can been observed respectively. Meanwhile, since the radius and charge of matrix lattice ions substituted by Eu 2+ do not match with those of Eu 2+ , the valence state of Eu 2+ is unstable. Eu 2+ is partly changed into Eu 3+ and the emission of Eu 3+ is obviously observed even under the condition of reduction atmosphere. If reaction temperature is more than 1 150 ℃, Al 2O 3 forms α Al 2O 3 structure, the f→f transition of Eu 2+ appears. If reaction temperature is less than 1 150 ℃, a mixed phase of α Al 2O 3 and γ Al 2O 3 is formed, the f→f transition of Eu 2+ disappears and a new band emission from d→f transition of Eu 2+ occurs.