The Luminescence of Eu2+in Mixed Phase System
LIU Ying-Liang, FENG De-Xiong, YANG Pei-Hui, SHI Qing-shan
1999, 20(7):
1021-1025.
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The dependence of the structure of the hosts on the Mion radius in MMgAl10O17(M=Be, Mg, Ca, Sr, Ba, Pb, Eu, Mn, Fe, Co, Ni, Zn, Cd, Sn) system was studied and the luminescence of Eu2+in the mixed phase system was discussed. When Mion radius is less than 0.10nm, the system MMgAl10O17constructs 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, Eu2+ion preferentially occupies lattice site of the cations in manegtoplumbite well matched with the radius and charge of Eu2+. There exists only d→f transition emission of Eu2+and no characteristic emission of Eu3+occurs in those hosts. In the mixed phase of spinel and α alumina, Eu2+can enter the lattice site of Mg2+ion or Al 3+ion and the d→f and f→f transition of Eu2+can been observed respectively. Mean-while, since the radius and charge of matrix lattice ions substituted by Eu2+do not match with those of Eu2+, the valence state of Eu2+is unstable. Eu2+is partly changed into Eu3+and the emission of Eu3+is obviously observed even under the condition of reduction atmosphere. If reaction temperature is more than1150 ℃, Al2O3forms α-Al2O3structure, the f→f transition of Eu2+appears. If reaction temperature is less than1150 ℃, a mixed phase of α-Al2O3and γ-Al2O3is formed, the f→f transition of Eu2+disappears and a new band emission from d→f transition of Eu2+occurs.
