| Indium tin oxide thin film is widely used in optoelectronic devices, such as flat panel displays, organic light-emitting diodes (OLED), electrochromic devices and solar cells, due to its high electrical conductivity and high transparency to visible light. At present, the preparation method of ITO thin film includes spray pyrolysis, electron beam evaporation, Sol-Gol, DC magnetron sputtering and chemical vapor deposition. Among them, DC magnetron sputtering is widely used owing to its low sputtering temperature, sputtering deposition thin film with good homogeneity and strong binding force. The density of ITO target is the key influence factor on the quality of ITO thin film. However, till now only some developed contries, such as Japan, Germany, South Korea and America master the key technique of preparing ITO target of high quality. Although the research and development of ITO target was carried out in the1990’s, and had gained some achievements in China, there are still lots of deficiencies, so it is of significance to enhance the basis work for the research and development of ITO target.In this study, using In2O3powder prepared by hydrolysis-hydrothermal treatment-calcination method and SnO2powder prepared by hydrolysis-hydrothermal treatment as raw materials, ITO slurries with mass ratio of In2O3/SnO2equal to9were prepared by ball-milling for24h. At first, the effects of pH value, amount of dispersant added on stabilities and rheological properties of slurries were investigated by means of Zeta potential measurement, sedimentation experiment and viscosity test; Secondly, we also studied systematically the compatibilities of dispersants and binders, as well as the effects of various factors on the characteristics of granulation powders obtained by spray-drying. At last, the effects of atmosphere and temperature on sintering behaviors of In2O3, SnO2as well as ITO powders were investigated by means of XRD, XRF and SEM.The results showed that:(1) pHiep (isoelectric point, IEP) value of ITO slurry with no dispersant added was about8.5, keeping pH value between4to10was unsuitable for preparing stable slurry. Only through adjustment of pH value, it was hard to maintain stability of ITO slurry of high solid content; Dispersants, CE64and KV5008, were suitable only for weak basic system due to the influences of ionic strength, but DIS54was approproate for a wider basic environment; Comparing the performances of reducing viscosity by adding disperant, DIS54was the best among the three disperants tested, CE64took the second place, while KV5008being the worst;(2) except for PVA124, DIS54had good compatibilities with PEG6000, BP05, BP17, but CE64had good compatibilities only with PEG6000, while KV5008had no good compatibilities with all four binders studied; under the condition of solid content of slurry of adding DIS54and BP0570wt%, the defects of granulation powder prepared by slurry spray-drying were the lest, and the apparent density were the highest; the apparent densities of powders gradually reduced with BP05concentration increasing (0～1.2wt%), but it had no influences on morphologies of powders.(3) In sintering processes in the temperature of1300～1600℃, both of In2O3and SnO2could decompose releasing O2, compared to In2O3, SnO2powders were easier to decompose; increasing oxygen partial pressure of sintering atmosphere was beneficial to inhibit their decompositions, and under O2atmosphere, ITO powders begin to decompose and lose weigh until as high as1500℃; After sintering under atmospheres of N2, air and O2for4h, SnO2still existed in ITO powders at1300℃, and at1400℃, SnO2phase disappeared along with the formation of a new phase, In4Sn3O12; With the further increase of sintering temperature, phase In4Sn3O12would disappear, and the higher the oxygen partial pressure of the sintering atmosphere, the higher the temperature in which phase In4Sn3O12disappears; In case of sintering under O2atmosphere, the lattice parameters of ITO powders obtained were the lowest and more stable, and moreover, the particle shrinkage during sintering was also more uniform, which were beneficial to preparing ITO target of high density. This dissertation contains62figures,8tables,165references... |
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