铟锡氧化物（ITO）粉体及高性能ITO靶材的制备与研究.pdf

I摘 要 本论文以热等静压制备铟锡氧化物ITO靶材的工艺流程为主线借助热分析TGA-DTAX 射线衍射XRD透射电镜TEM扫描电镜SEM能量分散谱EDS等分析手段系统地研究了球形和针状 ITO 粉末的制备以及热等静压制备 ITO 靶材的相关工艺成功地制备了外形规整的密度大于 99%的圆柱形 ITO 靶材 综述了 ITO 靶材市场需求的概况以及近几十年来 ITO 粉体ITO 靶材的研究现状和发展趋势简要地总结了热等静压法以及烧结法制备 ITO 靶材在制备工艺及相关技术上的异同点并在此基础上指出了本文研究的目的和意义 探讨了共沉淀反应过程的各种工艺参数对球形 ITO 粉体前驱体相结构等的影响并对前驱体向 ITO 固溶体的相转变过程进行了系统的表征发现在近中性和碱性环境下可以分别获得单相正交结构 InOOH 和立方结构 In(OH)3的前驱体且两者在向立方结构 ITO 固溶体转变的过程中前者相对于后者来说出现了刚玉型结构 ITO 固溶体中间相 在常压下1 atm用普通的浓缩或共沉淀法分别制备了微米级和纳米级针状ITO 粉末结果表明微米级 ITO 针的直径主要为 2 ~ 9m而且约 95%的针的长径比大于 6且针的含 Sn 量由表层向核心逐渐减小ITO 纳米针的直径主要为20 ~ 60nm长径比为 4 ~ 12ITO 前驱体纳米针是由直径为 3 ~ 4nm 的非常规整地排列成平行于轴向的纳米丝组成的且针中的纳米丝是沿 In(OH)3的[1 0 0]晶向择优取向生长的而 ITO 纳米针却是由其平坦面垂直于针的轴向的薄片状亚单元组成的 本文较为详细地研究了球形粉末后处理冷等静压工艺隔离材料等对热等静压制备 ITO 靶材的影响 并对热等静压制备 ITO 靶材的过程进行了计算机模拟结果表明 球形 ITO 粉末进行热处理后形成了晶格常数相对于 In2O3来说有所增大的单相 ITO 固溶体且粉体的摇实密度增加显著ITO 粉末还原后会在晶粒表面生成 In : Sn 为 97 : 3 的铟锡合金而这种铟锡合金对 ITO 粉末不润湿并形成球II形颗粒 且晶粒表面的 In 含量相对于 Sn 来说随着还原度的提高有增大的趋势 压力是制约 ITO 生坯冷等静压成型相对密度的关键因素ITO 靶材的热等静压过程中采用 1Cr18Ni9Ti 不锈钢制作包套利用氧化铝粉和石墨粉或六方 BN 粉的混合粉体作为隔离材料并对靶体辅以铂箔包裹进行热等静压时隔离方案起到了应有的隔离效果ITO 靶材的晶粒尺寸基本上为 1 ~ 10m 并且分布均匀靶材的断口为沿晶断裂靶材基本上全为 ITO 固溶体相但是在 32.252存在一个可能是由 InSn 的低价氧化物相或 InSn 金属相所产生的弱衍射峰采用未经致密化处理的粉末经热等静压制备的ITO靶材的晶粒分布很宽且局部存在异常长大的晶粒靶体内存在大量的内孔隙靶体的主晶相仍为 ITO 固溶体但靶体内部析出了含量约为 4.6 wt%的 SnO2相 本文还尝试了烧结法制备小块 ITO 靶材的工艺过程并对所制备的 ITO 靶材的断口相结构以及成分等进行了分析同时也初步探讨了热等静压 ITO 靶材磁控溅射获得 ITO 膜的制备过程并研究了相关工艺参数对膜的结构导电率表面形貌以及透光率等的影响结果表明在空气气氛中烧结的靶材中出现大量尺寸达 10 ~ 20m 的孔洞 靶材的 Sn 含量要低于纯氧气氛烧结的靶材 而且前者的ITO 固溶体的晶格常数小于后者的固溶体的晶格常数在低氧分压的条件下溅射膜的4 0 0面非常显著地择优平行于玻璃表面而随着氧压的升高却表现为膜的2 2 2面择优取向平行于玻璃表面随着氧压的升高膜的表面粗糙度起伏变小的同时膜的结构也越来越细腻膜的可见光透过率在氧分压增大的情形下有少许增大但是膜的导电率却略有下降 关键词铟锡氧化物ITO热等静压靶材粉末 IIIABSTRACT With the help of thermal analyses (TGA-DTA), X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersion spectra (EDS), etc., preparation of spherical or acicular indium-tin oxide (ITO) powders and preparation of ITO targets by hot isostatic pressing (HIP) were comprehensively investigated, and cylindrical ITO targets having a relative density of higher than 99% were obtained. The situations of heavy demands of ITO target and the research situations and development trends of ITO powders and ITO targets were generally reviewed. Moreover, the differences between sintering method and HIP method for preparation of ITO targets were briefly summarized, and the purposes and significances of the research works of the dissertation were indicated. Effects of technical parameters during co-precipitation processes on phase structures of ITO precursor powders were discussed, and transformation from ITO precursors to cubic ITO solid solutions were comprehensively investigated. Two kinds of ITO precursors, cubic In(OH)3 and orthorhombic InOOH, were prepared in alkali and neutral conditions respectively. Moreover, rhombohedral ITO solid solution appeared and acted as a transition phase during the transformation from InOOH to cubic ITO solid solution. Micron-scale and nano-scale acicular ITO powders were prepared in ambient atmosphere (1 atm) by concentration and co-precipitation methods respectively. The cross-sectional diameters of the most of micron-scale ITO aciculae were in the range of 2 to 9 m, and the aspect ratios of about 95% of aciculae were more than 6, and Sn content of the surface layer was higher than that of the bulk. The cross-sectional diameters of most of ITO nano-aciculae were mainly in the range of 20 to 60nm, and the aspect ratios were mostly in the range of 4 to 12. ITO precursor nano-aciculae were composed of very subtle nano-wires of 3 to 4 nm in cross-sectional diameter, and the IVnano-wires were regularly arranged to be parallel to the axial direction of ITO precursor nano-aciculae. ITO nano-aciculae were composed of flaky grains whose flat surfaces were perpendicular to the axial direction. Effects of heat-treatment parameters of spherical powders, technical parameters of cold isostatic pressing (CIP) and isolated materials on HIP of ITO targets were investigated in detail, and the processes of HIP of ITO targets were simulated by computer. Single ITO solid solution having larger lattice constant than In2O3 was formed after heat-treatment of spherical ITO powders, and the tap density of the powders was promoted greatly. In-Sn alloy having a weight ratio of 97 : 3 between In and Sn was formed on surfaces of grains of reduced ITO powders, and In-Sn alloy tended to form spherical particles for the reason of not wetting ITO. Moreover, the In content of In-Sn alloy increased with the increasing of reducing degrees of ITO powders. Pressure was the key parameter of relative density of ITO green compact by CIP. ITO green compact covered with Pt foil was capsuled with 1Cr18Ni9Ti stainless steel and isolated by mixing powders of Al2O3 and Graphite or BN before HIP, and the isolation method was excellent in HIP of ITO target. The grains of ITO target was uniformly in 1 ~ 10m in diameter, and the fracture of ITO target was absolutely along grain boundaries. The targe。