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近年来,一维纳米材料已成为广泛的研究热点.其中,Ⅱ-Ⅵ族掺杂半导体发光材料是一个重要的研究方向.研究者已通过不同的方法合成ZnS或CdS基掺杂纳米发光材料,以期得到基质与发光中心之间有效的能量传递,以及控制基质本身的缺陷发光.溶剂热便是其中一种较新的合成方法,通过它可以在相对温和的反应条件下得到均一的、结晶度较高的产品,在硫化物纳米发光材料的合成方面具有一定的优势.本文以乙二胺为溶剂,采用溶剂热方法制备出CdS︰Mn纳米棒,并系统研究了反应温度、硫镉比和反应时间对CdS︰Mn纳米晶的结晶度和发光性质的影响.(1)反应温度的影响.当[Cd(CH3COO)2]=0.0278mol·L-1,[TAA](硫代乙酰胺)=0.0556mol·L-1,[Mn(CH3COO)2]=0.000278mol·L-1时,分别在130,190,220,230,250℃恒温反应10h.随着反应温度的升高,CdS︰Mn纳米晶的结晶度逐渐提高.因为Mn2+掺杂进入CdS晶格,CdS纳米棒沿[001]晶向的生长优势逐步减弱并最终消失.在130～220℃之间,样品的发光强度变化不大.在220℃以上,样品的发光强度随反应温度的升高而迅速降低.(2)硫镉比的影响.当[Cd(CH3COO)2]=0.0278mol·L-1,[Mn(CH3COO)2]=0.000278mol·L-1时,改变TAA的浓度,分别采用0.5︰1,1︰1,1.5︰1,2︰1的硫镉摩尔比,在130℃恒温反应10h.发现随着硫镉比的提高,CdS︰Mn纳米晶的结晶度逐渐提高.当反应物中硫过量时,晶格缺陷以及表面悬空键数量降低,产品的发光强度随硫镉比升高而逐步提高.(3)反应时间的影响.当[Cd(CH3COO)2]=0.0278mol·L-1,[TAA]=0.0556mol·L-1,[Mn(CH3COO)2]=0.000278mol·L-1时,分别在130℃恒温反应1.5,2.5,4,6,10h.当反应时间少于4h时,CdS︰Mn纳米晶的结晶度迅速提高;而在4～10h之间,产品的结晶度变化不大.TEM图像显示了CdS︰Mn纳米棒的形成过程,只有当反应时间达到4h以上时,才能得到棒状产品.随着反应时间的延长,产品的发光强度先急剧降低,而后略微升高,这可能与纳米棒形成过程中产生的大量表面态有关.通过发光性质的研究,发现CdS基质的缺陷发光得到很好的抑制,产品在室温下即具有绝对优势的Mn2+发光(593nm),归于Mn2+的d-d(4T1-6A1)跃迁.激发光谱表明,本文所讨论的样品均显示出CdS基质的宽吸收,CdS基质与发光中心Mn2+之间存在有效的能量传递.综合考虑产品的形状与发光性质,当采用2︰1的硫镉比,不需要任何其他添加剂,在130℃反应10h制得Mn2+掺杂浓度为1%的CdS纳米棒,其在593nm附近的发光强度较强.CdS︰Mn纳米棒在纳米尺度电子和光子设备中具有潜在的应用价值.
In recent years, one-dimensional nanomaterials have become a hot research topic, among them, Ⅱ-Ⅵ family of doped semiconductor luminescent materials is an important research direction.The researchers have synthesized ZnS or CdS-based nanostructured luminescent materials by different methods, In order to obtain efficient energy transfer between the host and the luminescent center and to control the luminescence of the host’s own defects Solvent heat is one of the newer synthesis methods by which uniform and crystallinity can be obtained under relatively mild reaction conditions Higher product has some advantages in the synthesis of sulfide nano luminescent materials.In this paper, CdS: Mn nanorods were prepared by solvothermal method using ethylenediamine as solvent, and the reaction temperature, ratio of cadmium and cadmium Effect of reaction time on the crystallinity and luminescent properties of CdS: Mn nanocrystals. (1) Effect of reaction temperature. When [Cd (CH3COO) 2] = 0.0278mol·L-1, [TAA] = 0.0556mol·L-1 and [Mn (CH3COO) 2] = 0.000278mol·L-1, respectively, at 130,190,220,230,250 ℃ for 10h.With the increase of reaction temperature, the crystallinity of CdS: Mn nanocrystals gradually increased Because Mn2 + doping into the CdS lattice, CdS nanorods The growth advantage of [001] crystallographic orientation gradually weakened and eventually disappeared.When the temperature was above 220 ℃, the luminescence intensity of the sample decreased rapidly with the increase of reaction temperature. 2) when the concentration of [Cd (CH3COO) 2] = 0.0278mol·L-1 and [Mn (CH3COO) 2] = 0.000278mol·L-1, the concentration of TAA was changed, , 1︰1,1.5︰1,2︰1 sulfur and cadmium molar ratio at 130 ℃ for 10h.It was found that the crystallinity of CdS: Mn nanocrystals gradually increased as the ratio of sulfur and cadmium increased.When the content of sulfur When the content of Cd (CH3COO) 2] = 0.0278mol·L-1, the number of lattice defects and surface dangling bonds decreased. The emission intensity of the product gradually increased with the increase of the ratio of cadmium and cadmium. (3) , [TAA] = 0.0556mol·L-1, [Mn (CH3COO) 2] = 0.000278mol·L-1, respectively, at 130 ℃ for 1.5,2.5,4,6,10h.When the reaction time is less than 4h , The crystallinity of CdS: Mn nanocrystals increased rapidly, while the crystallinity of CdS: Mn nanocrystals changed little between 4 ~ 10h. The TEM images showed the formation of CdS: Mn nanorods only when the reaction time reached 4h , Can get stick products.With the extension of the reaction time, The luminescence intensity of the product first decreased sharply and then increased slightly, which may be related to the large number of surface states produced during the formation of nanorods.Based on the study of the luminescent properties, it was found that the defect luminescence of CdS matrix was well inhibited and the product was stable at room temperature (593nm), which is attributed to the dd (4T1-6A1) transition of Mn2 + .The excitation spectra show that the samples discussed in this paper all show the broad absorption of CdS matrix and the existence of effective interaction between CdS matrix and luminescence center Mn2 + Considering the shape and luminescent properties of the product, the CdS nanorods with Mn2 + doping concentration of 1% were prepared when the ratio of cadmium to cadmium was 2︰1 and no other additive was needed at 130 ℃ for 10h. 593nm near the strong light intensity.CdS: Mn nanorods in nanoscale electronic and photonic equipment has potential applications.