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双钒酸盐和稀土钼酸盐荧光粉的合成与发光性能研究

发布时间:2018-05-22 12:28

  本文选题:钼酸盐 + 钒酸盐 ; 参考:《广东工业大学》2017年硕士论文


【摘要】:白光LED(light emitting diode)因其高效率、低能耗、寿命长以及节能环保等一系列优点,引起人们的广泛关注。目前,通过将荧光粉与LED芯片组合,实现白光LED主要有两种方式:其一是利用蓝光LED芯片与黄色荧光粉组合;另一种是将紫外/近紫外LED芯片和三基色(红、绿和蓝光)荧光粉组合。其中第一种方案由于缺少红色成分而色温偏高,显色性较低。而对于第二种方案,目前所面临的主要挑战是研究出与近紫外LED芯片匹配的高效红色荧光粉。同时解决因不同材料间发光的相互吸收而导致的效率降低问题。因此,研究新型高效的红色或单相白色荧光粉显得尤为重要。本文中,我们合成了 K_3Gd(VO_4)_2:Eu~(3+)、Y_2Mo_4O_(15):Dy~(3+),Eu~(3+)和Gd_2Mo_4O_(15):Eu~(3+)系列荧光粉,通过X射线衍射(XRD)、扫描电子显微镜(SEM)和光致发光(PL)等对样品进行了分析,取得以下研究进展:1)采用固相法首次合成了K_3Gd(VO_4)_2:Eu~(3+)荧光粉。该荧光粉在紫外区域有很强的电荷迁移吸收带(峰值位于314 nm),在红光区域有很强的光发射(峰值位于617 nm)。增加Eu~(3+)离子的掺杂浓度可以增强荧光粉的发光强度,直至最佳掺杂浓度50 mol%,之后表现出浓度猝灭。K_3Gd(VO_4)_2特殊的晶格结构导致了高浓度猝灭的发生。激发波长由314 nm逐渐增加到346 nm时,K_3Gd(VO_4)_2:Eu~(3+)荧光粉的发光颜色从红色经暖白光到绿色区域连续可调,当激发波长为337 nm时,可得到暖白光的发射。K_3Gd(VO_4)_2:Eu~(3+)具有作为红色或单相白色荧光粉的潜在价值。2)采用固相法合成了新型颜色可调的Y_2Mo_4O_(15):Dy~(3+),Eu~(3+)系列荧光粉。单掺杂的Y_2Mo_4O_(15):Dy~(3+)荧光粉表现出Dy~(3+)离子的特征光发射~4F_(9/2)→~6H_(15/2)(蓝光)和~4F_(9/2)→~6H_(13/2)(黄光),黄蓝光之比为0.9左右。Dy~(3+)离子的最佳掺杂浓度为8 mol%。由发射谱和荧光衰减曲线分析发现,Y_2Mo_4O_(15):Dy~(3+),Eu~(3+)荧光粉中存在从Dy~(3+)到Eu~(3+)离子的能量转移过程。通过调整Dy~(3+)和Eu~(3+)离子的掺入浓度比,实现了 Y_2Mo_4O_(15):xDy~(3+),yEu~(3+)荧光粉的发光颜色在绿光、白光和橘红光区域内可调,当Dy~(3+)和Eu~(3+)的掺杂量分别为8 mol%和5 mol%时,可以得到白光发射。3)采用固相法首次成功合成了新型Gd_2Mo_4O_(15):Eu~(3+)荧光粉。晶体结构分析表明,Gd_2Mo_4O_(15)基质晶格同时含有[MoO_4]、[MoO_5]以及[MoO_6]钼酸盐基团。Eu~(3+)离子掺杂的Gd_2Mo_4O_(15)荧光粉,激发光谱呈现很宽的电荷迁移带(210-440nm),覆盖了紫外和近紫外区域,详细研究了多种[MoO_x]钼酸盐基团光吸收对电荷迁移带的贡献。发光中心Eu~(3+)离子主要占据非对称性格位,在紫外、近紫外和蓝光激发下,在618 nm处有较强的红光发射。Eu~(3+)离子的最佳掺杂浓度为50 mol%,浓度猝灭机制为交换相互作用。
[Abstract]:White LED(light emitting diode has attracted wide attention due to its advantages of high efficiency, low energy consumption, long life and energy saving and environmental protection. At present, there are two main ways to realize white LED by combining phosphor with LED chip: one is to combine blue LED chip with yellow phosphor, the other is to combine ultraviolet / near ultraviolet LED chip and tribasic color (red). Green and blue) phosphors. The first scheme has high color temperature and low color rendering due to the lack of red component. For the second scheme, the main challenge is to develop an efficient red phosphor that matches the near-ultraviolet LED chip. At the same time, the problem of reducing the efficiency caused by the mutual absorption of luminescence between different materials is solved. Therefore, it is very important to study new high-efficient red or single-phase white phosphors. In this paper, we have synthesized a series of K_3Gd(VO_4)_2:Eu~(3 phosphors, such as K_3Gd(VO_4)_2:Eu~(3, Y2Mo4O) and Gd_2Mo_4O_(15):Eu~(3). The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM) and photoluminescence (PL). K_3Gd(VO_4)_2:Eu~(3) phosphors were synthesized by solid phase method. The phosphor has a strong charge transfer absorption band in the UV region (the peak value is at 314 nm) and a strong light emission in the red region (the peak value is at 617 nm ~ (-1). The luminescence intensity of the phosphors can be enhanced by increasing the doping concentration of Eu~(3 ions until the optimum doping concentration is 50 mol.After the increase of the concentration quenching, the special lattice structure of K _ (3Gd) _ (VO _ 4) _ 2 leads to the occurrence of high concentration quenching. When the excitation wavelength was gradually increased from 314 nm to 346 nm, the luminescence color of the Phosphor was continuously adjustable from red through warm white light to green region, when the excitation wavelength was 337 nm. The emission of warm white light. K _ S _ 3G _ D _ (VO _ 3) has potential value as red or single-phase white phosphor.) A new type of Y_2Mo_4O_(15):Dy~(3 _ (3) with adjustable color has been synthesized by solid phase method. Single doped Y_2Mo_4O_(15):Dy~(3 phosphors exhibit Dy~(3) the characteristic light emission of the ion is 4F / 2) 6H / T 15 / 2 (blue light) and 4F / 9 / 2) the optimum doping concentration of the ions is 8 mol / 2 (yellow light, the ratio of yellow light to yellow light is about 0.9. Dy3) ion, the optimum doping concentration is 8 mol / 2 (blue light) and 4F / 2 / 2 (blue light ratio is 0. 9%. Dy3) ion doping concentration is 8 mol-1 / 2, the optimum doping concentration is 8 mol-1 / 2 (yellow light / blue light ratio is 0. 9% 路Dy3). From the analysis of emission spectrum and fluorescence attenuation curve, it is found that there is an energy transfer process from Dy~(3) to Eu~(3) in the Phosphor. By adjusting the concentration ratio of Dy~(3) and Eu~(3), the luminescent color of Y_2Mo_4O_(15):xDy~(3 Phosphor can be adjusted in green, white and orange region. When the doping amount of Dy~(3) and Eu~(3 is 8 mol% and 5 mol%, respectively, the luminescent color of the phosphor can be adjusted in the region of green, white and orange light, respectively, when the doping amounts of Dy~(3) and Eu~(3 are 8 mol% and 5 mol%, respectively. White emission. 3) A novel Gd_2Mo_4O_(15):Eu~(3) phosphor was synthesized successfully by solid phase method for the first time. The crystal structure analysis shows that there are [MoO_4], [MoO_5] and [MoO_6] molybdate group. EUON3) doped with Gd2Mo4OO15) phosphors, and the excitation spectra show a wide charge transfer band of 210-440 nm, covering the ultraviolet and near ultraviolet regions, and the crystal structure analysis shows that the Gd2Mo4OOC15) matrix lattice also contains [MoO_4], [MoO_5] and [MoO_6] molybdate group .Euf3) ions doped with Gd2Mo4OH15) phosphors, and the excitation spectra show a wide charge transfer band of 210-440 nm. The contribution of light absorption of various [MoO_x] molybdate groups to the charge transfer band has been studied in detail. The luminescent center Eu~(3) ion mainly occupies the asymmetric character position. Under the excitation of ultraviolet, near ultraviolet and blue light, the best doping concentration of red light emission. EUC 3) ion at 618nm is 50 mols. The mechanism of concentration quenching is exchange interaction.
【学位授予单位】:广东工业大学
【学位级别】:硕士
【学位授予年份】:2017
【分类号】:TN312.8;TN104.3

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