Preparation of (La_{1 − x}Sr_x)MnO_{3 − δ} thin films on Si (100) substrates by a metal-organic decomposition method for smart radiation devices

(La_{1 − x}Sr_x)MnO_{3 − δ} (LSMO) thin films were prepared on Si(100) substrates using a metal-organic decomposition (MOD) technique for smart radiation devices used for thermal control in spacecraft. The 6 wt% concentration MOD precursor solutions were spin-coated on Si substrates. The coated films were dried at 90 °C and pyrolytically decomposed at 530 °C. Finally, they were annealed in air at 750 °C to obtain dense, polycrystalline, and single-phase perovskite LSMO films. A ferromagnetic-paramagnetic phase transition was observed close to room temperature in a LSMO film. The thermal emittance of the film was changed as a result of this phase transition. The phase transition temperature increased with an increasing Sr ratio at the A-site of the LSMO and decreased after annealing under a reduced atmosphere. Based on this result, we propose that the temperature range where the thermal emittance is widely variable can be finely tuned on demand with post-annealing.