纳米级ITO粉体对烧结法制备靶材的影响

Effect of Nanosized ITO Powders on Preparation of ITO Targets by Sintering Method

摘要:

采用化学共沉淀法制备ITO前驱物，分别于600及1000 ℃下热处理前驱物，得到两种ITO粉体。粉体模压成型得到素坯，在400~1550 ℃内采用烧结法、氧气氛下烧结素坯制备出ITO靶材。对粉体及靶材进行表征和分析，研究了烧结过程中晶粒生长情况、靶材微结构与温度之间关系及靶材的失氧现象。得出600 ℃粉体为单相ITO固溶体、粒径为15 nm，1000℃粉体有少量SnO2析出、粒径为28 nm且其分散性和晶化程度优于600 ℃的粉体。两种粉体烧结制备靶材过程符合Coble固相烧结理论，1550 ℃时晶体出现类似二维成核生长方式的生长台阶。靶材密度随温度升高而增加，1550 ℃时随保温时间延长而增加。靶材致密化过程由团聚程度及团聚体大小决定，1000 ℃粉体制备的靶材密度高于600 ℃粉体所制靶材。两类靶材含氧量均低于理论值，1000 ℃粉体所制靶材含氧量高于600 ℃的含氧量。

Abstract:

Two kinds of nanosized indium-tin-oxide (ITO) powders were prepared by heating the ITO precursors at 600 and 1000 oC respectively. The compacts were obtained by press molding of the powders. Then ITO targets were prepared by sintering the compacts at 400-1550 oC in oxygen atmosphere. The powders and the targets were characterized. The grain growth during sintering, the relationship between the targets’ microstructure and the sintering temperature, and the oxygen content of the targets were investigated. The results show that powders prepared by heating the ITO precursors at 600 oC (600 oC ITO powder) are single phase, and their grain size is 15 nm. Powders prepared by heating the ITO precursors at 1000 oC (1000 oC ITO powder) contain a little SnO2, and the grain size is 28 nm. 1000 oC ITO powders exhibit better dispersivity and keep higher crystallization degree. The sintering process of these two kinds of ITO powders corresponds with Coble Solid Phase Sintering process. When the sintering temperature is 1550 oC, crystal growth steps similar to the steps appearing in the two-dimensional nucleation growth can be observed. ITO targets’ density increases as the temperature rises and holding time extends. The density of ITO targets made from 1000 oC ITO powders is higher than that of the targets made from 600 oC ITO powders. This phenomenon indicates that targets’ densification is determined by the degree of agglomeration and the size of agglomerates. Both types of targets contain less oxygen than the theoretical value. And the oxygen content of targets made from 1000 oC ITO powders are higher than that of targets made from 600 oC ITO powders.