Research on the optimization of electrical properties for low-temperature sintered indium tin oxide slurry

In this paper, an indium tin oxide (ITO) and indium oxide (In₂O₃) slurry that can be used for low-temperature sintering was prepared, after which an ITO/In₂O₃ thermocouple was prepared on an aluminum oxide (Al₂O₃) ceramic substrate using a screen-printing process for verifying its comprehensive performance. The samples were treated at an annealing temperature of 900 °C for different times. The characterization results show that when the annealing time is set to 3 h, the ITO film has the best crystallization effect. Moreover, under this annealing condition, Sn²⁺ ions are more inclined to transform into Sn⁴⁺ ions, promoting the release of additional free electrons, which significantly enhances the thermoelectric effect. The test result of its electrical conductivity is 134.2 s/cm. Within the temperature range of 900 °C, the thermocouple has an ultra-high Seebeck coefficient of 410.91 μV/°C, and the peak output voltage is 332.8 mV. The maximum repeatability error is 2.745 %. It can be seen that the slurry prepared in this paper has excellent electrical properties after sintering at 900 °C, and is expected to become a feasible substitute in the field of conductive slurry of low temperature co-fired ceramic (LTCC).