低温溶液法制备ZnO：Co纳米粉体及性质研究
发布时间：2018-08-10 18:55
【摘要】：ZnO具有较高的激子束缚能(60 meV)和较宽的禁带宽度(3.37 eV),在压电、光电设备等领域表现出巨大的应用潜力。通过向ZnO中掺入其他元素,可以有效地调整其内部结构和形貌,改善其性能,从而扩大ZnO的应用范围,所以近年来有关纳米ZnO掺杂的研究迅速发展起来。Co作为一种典型的过渡金属元素,具有丰富的表面态和与Zn~2+相似的离子半径,更容易进入到ZnO晶格与之溶为一相,可以有效调节ZnO的禁带宽度,进而调控其光学性能和应用。同时,Co具有磁性,掺入到ZnO晶格内可形成ZnO基稀磁半导体(DMS),从而将ZnO的应用扩展到电子自旋设备、探测器等领域。于是,制备和研究集光、磁效应于一体的ZnO基稀磁半导体材料具有极其重要的意义。本论文以ZnCl_2、CoCl_2为原料,分别选用NaOH和NH_3·H_2O为沉淀剂,采用常压沸腾回流法,成功制备了ZnO:Co纳米粉体,利用XRD、FESEM、EDS和XPS对产品的结构和形貌进行了表征,利用UV-vis、PL和PPMS研究了样品的光学性质和磁性质。 本论文的主要内容如下: (1)以ZnCl_2、CoCl_2为原料,选用NaOH和NH_3·H_2O为沉淀剂,采用常压沸腾回流法成功制备了ZnO:Co纳米粉体,探索了药品滴加顺序、溶液碱度、初始Zn~2+离子浓度、沸腾回流时间等最适宜合成条件。以NaOH为沉淀剂,在锌碱比1:3.6～1:4.0的中碱度溶液中制备了掺杂效果良好,长约3μm,平均直径200 nm,长径比高达15的ZnO:Co纳米晶须;在锌碱比1:9.0的高碱度溶液中,通过对前驱物进行40℃预搅拌处理,制备出长径比较大、形貌规则的ZnO:Co纳米棒。以NH_3·H_2O为沉淀剂,在锌碱比1:4.0的溶液中制备了形貌特殊的ZnO:Co放射性纳米管团簇。 (2)以ZnCl_2、CoCl_2为原料,选用NaOH和NH_3·H_2O为沉淀剂,在ZnO:Co最适宜的合成条件下制备了不同掺杂浓度的ZnO:Co纳米粉体,考察了掺杂浓度对样品结构和形貌的的影响,研究了样品的光学性质和磁性质。结果表明,Co以+2价的Co~2+形式进入到ZnO晶格取代了部分Zn~2+,没有改变ZnO六方纤锌矿的结构;掺杂以后样品的形貌发生较大变化。Co~2+掺杂后导致ZnO禁带宽度变窄,样品的紫外吸收带边和紫外发光峰位均向高波长红移;由于氧空位缺陷引起的黄绿光发射能量与Co~2+的4~A_2(F)→2~A1(G)电子跃迁能量发生共振产生能量转移,导致掺杂样品的黄绿光发射发生猝灭现象。样品在合适的Co掺杂浓度下表现出室温铁磁性,源于氧空位引起的杂质带上Co~2+-Co~2+铁磁性耦合作用;掺杂浓度较高时,占据晶格中彼此相邻最近格位的掺杂离子之间发生Co~2+-Co~2+反铁磁性耦合作用,而使样品在外加磁场作用下表现为顺磁性。
[Abstract]:ZnO has a high exciton binding energy (60 meV) and a wide band gap (3.37 eV), which shows great potential applications in piezoelectric, optoelectronic devices and other fields. By adding other elements into ZnO, the internal structure and morphology of ZnO can be adjusted effectively, its performance can be improved, and the application of ZnO can be expanded. Therefore, in recent years, the research on nano-ZnO doping has developed rapidly. As a typical transition metal element,. Co has abundant surface states and ionic radii similar to Zn~2, so it is easier to enter the ZnO lattice and dissolve into one phase. The band gap of ZnO can be adjusted effectively, and then its optical properties and applications can be regulated. At the same time, Co is magnetic and doped into ZnO lattice to form ZnO based dilute magnetic semiconductor (DMS), which extends the application of ZnO to electronic spin equipment, detector and so on. Therefore, the preparation and study of ZnO based diluted magnetic semiconductor materials with optical and magnetic effects are of great significance. In this paper, ZnCl2CoCl2 was used as raw material, NaOH and NH_3 H2O were used as precipitators respectively, and ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling refluxing method. The structure and morphology of the products were characterized by XRD-FESEMEDS and XPS. The optical and magnetic properties of the samples were studied by UV-vis PL and PPMS. The main contents of this thesis are as follows: (1) NaOH and NH_3 H _ 2O were used as precipitators and ZnCl _ 2CoCl _ 2 was used as raw material, ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling reflux method. The order of dropping, the alkalinity of solution and the initial concentration of Zn~2 ion were explored. Boiling reflux time is the most suitable synthetic condition. Using NaOH as precipitant, ZnO:Co nanocrystalline whiskers with a length of about 3 渭 m, an average diameter of 200nm and a aspect ratio of up to 15 were prepared in a medium alkalinity solution with a ratio of 1: 3.6 to 1: 4.0, and a high alkalinity ratio of 1: 9.0. By pre-stirring the precursor at 40 鈩，
本文编号：2175893
[Abstract]:ZnO has a high exciton binding energy (60 meV) and a wide band gap (3.37 eV), which shows great potential applications in piezoelectric, optoelectronic devices and other fields. By adding other elements into ZnO, the internal structure and morphology of ZnO can be adjusted effectively, its performance can be improved, and the application of ZnO can be expanded. Therefore, in recent years, the research on nano-ZnO doping has developed rapidly. As a typical transition metal element,. Co has abundant surface states and ionic radii similar to Zn~2, so it is easier to enter the ZnO lattice and dissolve into one phase. The band gap of ZnO can be adjusted effectively, and then its optical properties and applications can be regulated. At the same time, Co is magnetic and doped into ZnO lattice to form ZnO based dilute magnetic semiconductor (DMS), which extends the application of ZnO to electronic spin equipment, detector and so on. Therefore, the preparation and study of ZnO based diluted magnetic semiconductor materials with optical and magnetic effects are of great significance. In this paper, ZnCl2CoCl2 was used as raw material, NaOH and NH_3 H2O were used as precipitators respectively, and ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling refluxing method. The structure and morphology of the products were characterized by XRD-FESEMEDS and XPS. The optical and magnetic properties of the samples were studied by UV-vis PL and PPMS. The main contents of this thesis are as follows: (1) NaOH and NH_3 H _ 2O were used as precipitators and ZnCl _ 2CoCl _ 2 was used as raw material, ZnO:Co nano-powders were successfully prepared by atmospheric pressure boiling reflux method. The order of dropping, the alkalinity of solution and the initial concentration of Zn~2 ion were explored. Boiling reflux time is the most suitable synthetic condition. Using NaOH as precipitant, ZnO:Co nanocrystalline whiskers with a length of about 3 渭 m, an average diameter of 200nm and a aspect ratio of up to 15 were prepared in a medium alkalinity solution with a ratio of 1: 3.6 to 1: 4.0, and a high alkalinity ratio of 1: 9.0. By pre-stirring the precursor at 40 鈩，
本文编号：2175893
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