Achieving high relative density and low resistivity in indium tin oxide targets via Bi2O3-CeO2 additive

Abstract

Indium tin oxide (ITO) target, an important raw material of ITO films, is difficultly prepared by traditional sintering due to the volatilization and partial dissociation at high sintering temperature. In this work, the high-density and low-resistivity ITO targets were prepared with Bi2O3-CeO2 additive at low sintering temperature. The effects of Bi2O3-CeO2 content and sintering temperature on the densification, phase composition, microstructure, mechanical properties and electrical resistivity of ITO targets were systematically investigated. The results revealed that the Bi2O3-CeO2 addition reduced sintering temperature by 50 ℃, and the ITO target with 1.0 wt% Bi2O3-1.0 wt% CeO2 had the maximum relative density of 99.57%, surpassing additive-free ITO target. The dense microstructure at low sintering temperature was attributed that Bi2O3 could convert solid phase sintering into liquid phase sintering. Notably, the ITO target with 1.0 wt% Bi2O3-1.0 wt% CeO2 also had the minimum resistivity of 1.82 × 10−4 Ω·cm, which was due to more free electrons generated by CeO2 doping and the dense microstructure. In addition, the grain growth kinetics was applied to calculate corresponding diffusion data, namely, the grain growth exponent (n = 7.4), growth rate constant (k = 4.211 × 1023) and growth activation energy (Q = 394.79 kJ/mol). This work provides a strategy to prepare high-quality ITO targets and presents great potential for the low-temperature sintering on other ceramic materials.