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采用球磨法制备了不同浓度Cr_2O_3掺杂的Al_2O_3粉体,并在700℃、1200℃空气中退火2 h。1200℃退火后样品,除掺杂浓度为1.6%的样品中出现少量γ-Al_2O_3相外,其余样品相均为纯α-Al_2O_3。样品晶格常数随着Cr~(3+)离子浓度的增加而增加。采用波长为579 nm的激发光源对佯品进行荧光光谱检测发现所有样品在469-492 nm波段,均出现F~+心所引起的缺陷发光峰.1200℃退火的所有样品都出现一个由Cr~(3+)离子中电子由2A能级到~4A_2能级跃迁引起的在694 nm的强烈发光带,掺杂浓度为0.3%时发光强度最高。当掺杂浓度高于0.3%时,样品中Cr~(3+)未能完全替代Al_2O_3中的Al~(3+)离子,出现耦合,产生浓度猝灭现象,导致该波长发光强度减弱。对比而言,700℃退火样品仅掺杂浓度为0.3%时出现694 nm的发光,且强度较低。
Cr 2 O 3 doped Al 2 O 3 powders with different concentrations were prepared by ball milling and annealed in air at 1200 ℃ for 2 h at 700 ℃. After annealed at 1200 ℃, except for a small amount of γ-Al 2 O 3 phase in the sample with 1.6% doping concentration, the other samples were pure α-Al 2 O 3. The lattice constant increases with the increase of Cr 3+ ion concentration. Fluorescence spectrum of the femto product was detected by using an excitation light source with a wavelength of 579 nm, and all of the samples showed flaw peaks caused by F ~ + in the 469-492 nm band. All the samples annealed at 1200 ℃ showed a Cr- (3+) ions have strong emission band at 694 nm caused by the transition from 2A level to ~ 4A_2 level, and the emission intensity is the highest when the doping concentration is 0.3%. When the doping concentration is higher than 0.3%, the Cr 3+ in the sample can not completely replace the Al 3+ ion in Al 2 O 3 and the coupling occurs, resulting in quenching of the concentration, which leads to the decrease of the luminescence intensity at this wavelength. In contrast, the samples annealed at 700 ° C exhibited 694 nm emission at 0.3% doping concentration, with lower intensity.