Theoretical simulation of pre-sintering effect and improvement of electrical transport properties of La0.7Ca0.18Sr0.12MnO3 film prepared by spin coating method

Perovskite manganites Lax(Ca1-ySry)1-xMnO3 have drawn the plentiful attention owing to their distinctive physical properties. Their unique properties make them an ideal candidate for high-sensitivity and uncooled bolometric applications. Optimized La0.7Ca0.18Sr0.12MnO3 (LCSMO) films were grown on (00l) LaAlO3 substrate at different pre-sintering temperature (Tps) via sol–gel spin coating method. According to the test results of microstructure, internal strain, Mn ion valences and surface morphology, electrical transport properties are restricted by MnO6 octahedron distortion and film crystallinity affected by the change in Tps. The microstructure growth was improved and the surface morphology tended to grow in a cross-like structure with high crystallinity by optimizing Tps. Double exchange mechanism and internal strain were enhanced with the increase in Tps. Thereby, due to the enlarging MnOMn bond angle and enhancing MnO covalency, the temperature (Tk) corresponding to temperature coefficient of resistivity (TCR) was increased gradually as Tps increased. The TCR value of LCSMO film reached a maximum value (10.82 %/K) and Tk reached room temperature (302.03 K) at Tps = 1123 K. The theoretical foundation of the pre-sintering effect has been supplemented, helping to understand the influence of pre-sintering on film growth and electrical transport properties.