科研之友
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摘要
The perovskite BaMnO3 nanorods with fixed width of 60-100 nm and tunable length of 600-800 nm, 400-600 nm and 150-300 nm have been prepared by using a composite-hydroxide-mediated method with adding 0, 3 and 7 ml H2O. The ratio of surface area to volume (SVR) increases with decreasing length of the nanorods. The X-ray diffraction pattern of the nanorods indexes a hexagonal phase BaMnO3 with space group P6(3)/mmc. Two absorption peaks are observed in ultraviolet-visible absorption spectra measured on the BaMnO3 nanorods at room temperature. The peak centred at 402 nm is sensitive to length of the nanorods. The band and density of states of BaMnO3 are calculated by density-functional theory. The results show that the peak centred at 402 nm is assigned to a transition of 2P down arrow to Mn t(2g) down arrow states, while the peak centred at 301 nm is corresponding to the O 2P up arrow to Mn e(g) up arrow states. The increasing of SVR brings the more oxygen surface layer areas and oxygen vacancies, which decreases the bandgap, and leads to the red shift of emission and weakening of the absorption peak centred at 402 nm.
- 出版日期2012-9
- 单位重庆大学
