Heater-Assisted Intense Pulsed Light Irradiation for Lanthanum Strontium Cobaltite Thin Film Electrode Fabrication
Authors: Park Jun-Sik , Lee HoJae , Kim Young-Beom 
Published: February 2020

The wet chemical processes show many benefits over vacuum processes on account of their simplicity, versatility, and low cost. The films prepared via this method are advantageous for industrial applications. But inevitably, these processes require post-treatment for sintering and conventional method like furnace is still costly in terms of time and energy.
Intense pulsed light irradiation is an innovative approach to proceed the post heat-treatment rather than using furnace which spend much time for process. By employing Xenon arc lamp that be used to cover the spectral range from about 400nm up to 950nm (1), white flash light can be irradiated and sinter the specimen in a moment. In this study, we employed metal organic decomposition method for lanthanum strontium cobaltite (LSCO) film coating and introduce two steps of irradiation process for effective sintering (2); pre-heating step to get rid of remnant organics and main-heating step for further sintering process. Pre-heating is long and weak step that gradually increases the temperature while main-heating is short and strong step that instantly increases. But in case of main-heating, there are some potential risks with process. During main-step process, substrates could be exposed to high flash light energy and could eventually be shattered by thermal shock.
For this reason, we had tried to relieve the shock by reducing the input power of intense pulsed light irradiation. Considering that photo-thermal effect is the one of the factor of white flash light sintering process, the shortage of energy for sintering process was filled by employing heat energy supplied by bottom heater. Varying the bottom temperature to RT, 200oC and 300oC, the input energy required for optimized LSCO film was obviously decreased with temperature. Diffraction pattern obtained by XRD also confirms the effect of bottom heat by indicating perovskite peak only for 200oC and 300oC, while flash light irradiated sample at room temperature shows nothing on account of energy shortage. In addition, unlike irradiated sample at room temperature, FE-SEM images of heat-assisted intense pulsed light LSCO show porous surface morphology, which is suitable for cathode of solid oxide fuel cells (SOFCs).
Here, electrolyte supported solid oxide fuel cell was fabricated by heat-assisted intense pulsed light irradiation method. Thermal shock to electrolyte was slacken off, and porous cathode could be obtained with this method. Electrolyte substrate could hardly not withstand high irradiation energy under room temperature. Fabricated solid oxide fuel cell shows reasonable performance under low temperature regime. The significance of this work is the feasibility of heater-assisted intense pulsed light irradiation method. These result shows the possibility to expand the applicable targets which are deposited on thermal shock vulnerable substrate.

References

H.-J. Hwang, W.-H. Chung and H.-S. Kim, Nanotechnology, 23, 485205 (2012).

E.-B. Jeon, S.-J. Joo, H. Ahn and H.-S. Kim, Thin Solid Films, 603, 382 (2016).