Synthesis, structure and optical properties of Co-doped MgGa₂O₄/SiO₂ nano-glass-ceramic composites

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• 作者：Xiulan Duan ; ^{xlduan@sdu.edu.cn} ; Yuanchun Wu ; Xinqiang Wang ; Fapeng Yu ; Huaidong Jiang
• 关键词：Co ; MgGa2O4/SiO2 ; Sol&ndash ; gel method ; Nano-glass-ceramics ; Cation distribution
• 刊名：Applied Surface Science
• 出版年：2013
• 出版时间：1 July, 2013
• 年：2013
• 卷：276
• 期：Complete
• 页码：613-619
• 全文大小：2455 K

文摘

Co-doped MgGa₂O₄/SiO₂ nano-glass-ceramic composites with the composition of (1 ? y) Co_xMg_1?xGa₂O₄-ySiO₂ (0 ¡Ü x, y ¡Ü 1) were synthesized by the sol-gel method and characterized by X-ray powder diffraction and transmission electron microscopy. X-ray photoelectron spectroscopy was used to study the chemical environments of cations and oxygen in the nanocomposites as a function of annealing temperature, cobalt content and SiO₂ content. The results show that Ga³⁺ and Mg²⁺ ions occupy both the tetrahedral and octahedral sites of spinel structure in the samples. The inversion parameter (two times the fraction of Ga³⁺ ions in the tetrahedral sites) of the nanocomposites is relatively larger in comparison with that of ZnGa₂O₄, and the value decreases with the increase of annealing temperature and silica concentration, while increases with cobalt-enrichment. All the Co-doped samples exhibit the intense absorption peak at ~600 nm, which is characteristic of tetrahedral Co²⁺. But only in the composites of Co_0.3Mg_0.7Ga₂O₄ and 0.6Co_0.6Mg_0.4Ga₂O₄-0.4SiO₂, the absorption band at 300-500 nm characteristic of octahedral Co²⁺ ions is observed. The intensity of the absorption peak corresponding to octahedral Co²⁺ ions increases with decreasing annealing temperature for the Co_0.3Mg_0.7Ga₂O₄ nanocrystals.