Facile fabrication of highly conductive and dense indium tin oxide targets by cold sintering assisted process

Indium tin oxide (ITO) ceramic sputtering targets are widely used to produce electrically conductive transparent thin films for various optoelectronic devices. However, it is challenging to produce high quality targets due to the poor sinterability of ITO powders. Conventional sintering of polycrystalline ITO ceramics is prevalently performed at very high temperatures (1550–1650 °C) for very long time (10 h) in an oxygen atmosphere. Here, we produced ITO targets with high density and low resistivity by cold sintering assisted process at reduced sintering temperature and time. ITO ceramics were first prepared via cold sintering process (CSP) at 250 °C for 1 h. As-CSPed samples consisted of nanocrystalline grains and amorphous phase. Subsequently, post-annealing was conducted in air at 1400 °C for 4 h to facilitate both crystallisation of the amorphous phase and densification. For comparison, ITO ceramics were also produced by conventional sintering at the identical condition (1400 °C for 4 h). The samples produced by cold sintering assisted process exhibited much higher density of 98.6 % and lower resistivity of 3.63 × 10 −4 Ω·cm than the corresponding values (63.4 % and 2.10 × 10 −3 Ω·cm) from conventionally sintered samples. These optimal properties attained from this work are comparable to the best reported values for bulk ITO ceramics so far. More importantly, such a high performance is achieved by a cost-effective processing route without atmospheric control and sintering aids. Thus, our results demonstrate the potential of alternative densification strategy for facile fabrication of high-quality ITO targets.