ZnS基纳米晶的制备及其性能研究

发布时间：2018-07-26 18:19

【摘要】：本文利用热溶液注入法和水热法合成了 ZnS,ZnS:Eu~(3+),ZnSexS1x纳米晶,制备方法操作简单,成本低,相对绿色环保,合成产物具有较好的荧光性能。利用第一性原理计算了材料的电子结构,并利用XRD,TEM,SEM,荧光光谱,UV-vis吸收光谱等对所得纳米晶进行了表征。具体内容如下:(1)构建了立方相ZnS的1×1×2的超胞,并在此基础上,通过添加和删减原子,建立了具有不同缺陷的ZnS空间模型,利用第一性原理计算了不同缺陷的形成能和电子结构,分析了不同缺陷对能带结构和态密度的影响。采用热溶液注入法合成了不同Zn/S比例的ZnS纳米晶。XRD衍射分析表明所得产物均为立方闪锌矿结构,TEM图显示所得纳米晶的颗粒近似球形,分散性良好,HRTEM图可以看出明显的晶格条纹,不同Zn/S比制备的ZnS纳米颗粒粒径在3nm到7nm之间。样品的发射光谱的主峰位置在418nm、433nm、468nm和500nm,分别对应着四个缺陷能级跃迁。(2)构建了立方相ZnS的2×2×2的超胞,其中,分别用Eu原子取代其中的一个Zn原子和两个Zn原子,利用第一性原理计算了掺杂Eu的ZnS的电子结构,分析了不同掺杂浓度对能带结构和态密度的影响。采用热溶液注入的方法合成了不同掺杂浓度的ZnS:Eu~(3+)纳米晶,XRD图谱显示纳米晶为立方闪锌矿结构。TEM表明颗粒近似球形,随着掺杂浓度的增加,粒径逐渐增大。HRTEM可见明显晶格条纹。EDS图谱中观察到了 Eu元素的能量峰。测试了纳米晶的荧光光谱,发射光谱在595nm、621nm和701nm处出现了 Eu~(3+)的特征峰,其中位于621nm处的发射峰强度最大。激发光谱中位于395nm处的激发峰强度最大,随着掺杂浓度的增加,色坐标向白色区域靠近。(3)在立方相 ZnS 超胞的基础上,构建了 ZnSe_xS_(1-x)(x=0.20,0.33,0.50,0.67,0.80,1.00)空间模型,用第一性原理计算了其电子结构,分析了不同x值对其能带和态密度的影响。利用热溶液注入法合成了 ZnSe_xS_(1-x)纳米晶,随着x值的增加,XRD衍射峰向小角度方向偏移,颗粒粒径从3.74nm逐渐增大到了 4.33nm。测试了纳米晶的荧光光谱,在440nm激发下,发射峰从518nm红移到了 544nm;监测528nm,得到的激发光谱的激发峰从423nm红移到了 475nm。(4)利用水热法合成了 ZnS微晶,并且改变了制备过程中前躯体的Zn/S比例和水醇比,得到了具有不同发光性能的ZnS微晶,XRD显示纳米晶为立方闪锌矿结构,发射光谱出现了由硫空位和锌空位缺陷引起的两个发射峰,分别位于483nm和586nm,随着Zn/S比例的变化,两个发射峰的相对强度会随之发生变化。当水醇比为1:1时,发射峰强度最大,半高宽最小。
[Abstract]:In this paper, ZnS: ZnSexS1x nanocrystalline was synthesized by hot solution implantation and hydrothermal method. The preparation method is simple, low cost, relatively green and environmentally friendly. The synthesized product has better fluorescence properties. The electronic structure of the material was calculated by first principles. The nanocrystalline was characterized by XRDX Tem SEM, fluorescence spectra and UV-vis absorption spectra. The main contents are as follows: (1) 1 脳 1 脳 2 supercell of cubic ZnS is constructed. On this basis, by adding and deleting atoms, the ZnS space model with different defects is established, and the formation energy and electronic structure of different defects are calculated by first principle. The effects of different defects on the band structure and density of states are analyzed. The ZnS nanocrystals with different Zn/S ratios were synthesized by hot solution injection method. The results showed that the nanocrystalline particles were almost spherical, and the lattice stripes were obvious in the well-dispersed ZnS images. The size of ZnS nanoparticles prepared with different Zn/S ratios ranged from 3nm to 7nm. The main peaks of the emission spectra of the samples are at 418 nm, 433 nm, 468 nm and 500 nm, respectively, corresponding to the transition of four defect levels. (2) the supercell of 2 脳 2 脳 2 in cubic phase ZnS is constructed, in which one Zn atom and two Zn atoms are replaced by EU atom, respectively. The electronic structure of ZnS doped with EU was calculated by first principle, and the influence of doping concentration on the band structure and density of states was analyzed. The XRD patterns of ZnS _ (3) nanocrystalline with different doping concentrations were synthesized by hot solution injection. The results show that the nanocrystalline is cubic sphalerite structure. The energy peak of EU element was observed in the lattice stripe. EDS diagram. The fluorescence spectra of nanocrystals were measured. The emission spectra showed the characteristic peaks of EU3 at 621nm and 701nm, and the emission peaks located at 621nm were the most intense. The intensity of excitation peak located at 395nm is the largest in the excitation spectrum. With the increase of doping concentration, the chromatic coordinate is closer to the white region. (3) based on the cubic phase ZnS supercell, the spatial model of ZnSexS1-x (x0.200.33O0.500.500.50,0.670.800.801.00) has been constructed, and its electronic structure has been calculated by the first principle. The effects of different x values on the energy band and density of states are analyzed. ZnS _ XS _ (1-x) nanocrystals were synthesized by hot solution injection method. With the increase of x value, the diffraction peak shifted to small angle, and the particle size gradually increased from 3.74nm to 4.33 nm. The fluorescence spectra of nanocrystals were measured. The emission peak shifted from 518nm red to 544 nm under 440nm excitation, and the excitation peak from 423nm red to 475 nm was obtained by monitoring 528 nm. (4) ZnS microcrystals were synthesized by hydrothermal method. By changing the Zn/S ratio of precursor and the ratio of water to alcohol, the nanocrystalline ZnS with different luminescent properties was obtained, which shows that the nanocrystalline is cubic sphalerite structure. There are two emission peaks caused by sulfur vacancy and zinc vacancy defect in the emission spectrum, which are located at 483nm and 586 nm, respectively. With the change of Zn/S ratio, the relative intensity of the two emission peaks will change. When the ratio of water to alcohol is 1:1, the emission peak intensity is the largest and the half maximum width is the smallest.
【学位授予单位】：河北大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TB383.1

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