镧
结晶学
离子
八面体
化学
吸收光谱法
锰
退火(玻璃)
晶体结构
单晶
谱线
发光
无机化学
材料科学
复合材料
有机化学
物理
量子力学
光电子学
天文
作者
F. Laville,Didier Gourier,A.M. Lejus,D. Vivien
标识
DOI:10.1016/0022-4596(83)90111-1
摘要
New lanthanum aluminates LaMAl11O19 (M2+ = Ni, Co, Mn, Mg1−xMnx, 0 ≤ x ≤ 1), with magnetoplumbite-like structure have been obtained as single crystals. This paper is particularly devoted to the Mn2+ and Mg2+Mn2+ mixed compounds, which exhibit promising luminescent properties. Several characteristics of the crystals are given. The absorption spectra of the materials, as grown, are assigned to Mn2+ ions in tetrahedral sites. After annealing in air new absorptions attributed to octahedral Mn3+ ions, appear. The ESR spectra of Mn2+ in all these crystals exhibit axial symmetry. For x ≤ 0.25 they arise from isolated Mn2+ ions in slightly distorted tetrahedral sites and reveal a strong disorder effect. For x ≥0.5 the spectra consist of a single line, attributed to clusters of magnetically interacting Mn2+ ions.
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