Tuning strain-stress and electron-lattice effects to enhance electrical transport properties of La0.7Ca0.25K0.05MnO3 films via optimizing sintering temperatures

Abstract

Facile-prepared films with a high-temperature coefficient of resistivity (TCR) are crucial for application in high-sensitivity bolometers. In this study, La0.7Ca0.25K0.05MnO3 (LCKMO) films were grown on (001)-oriented La0.3Sr0.7Al0.65Ta0.35O3 (LSAT) substrates using the spin-coating method. Various sintering temperatures (900 °C ≤ Ts ≤ 1050 °C) were utilized in the film preparation, causing the lattice mismatch between films and substrate degraded. The effect of Ts on the strain state of films was investigated through X-ray diffraction (XRD) analysis. The distortion of MnO6 octahedra and the Mn–O bond were assessed using Raman and FTIR spectra, respectively. The structural perfection and elemental valence of films were adjusted via optimizing Ts. Meanwhile, the strain state and defect structure were effectively improved with Ts increasing. These results indicate that the LCKMO films with high crystalline quality can be achieved by optimizing the sintering process. The TCR of LCKMO films was modified. When Ts at 1000 °C, the LCKMO films exhibit the remarkable TCR of 16.29% K-1 at 269.54 K, indicating the substantial potential of LCKMO films in infrared bolometers.