Exploration of electrical conduction mechanisms via modulating sintering period of La0.67Ca0.33MnO3 films in various phase regions

Perovskite manganese oxide films have garnered significant attention due to their unique and diverse physical properties. In this work, La 0.67 Ca 0.33 MnO 3 (LCMO) films are prepared on LaAlO3 (00l) substrates using the sol-gel spin coating method with varying sintering period (Ps). By optimizing P s , improvements were observed in the films' structure, morphology, ionic valence, and temperature-dependent resistivity. The reduction in Mn-O bond length and the increase in Mn-O-Mn bond angle change the degree of MnO6 distortion, resulting in an increased e g bandwidth. As P s increased, the LCMO films exhibited better crystalline quality. The improved Mn4+/Mn3+ ratio strengthened the double exchange effect, facilitating the carrier hopping of the e g electrons. Analyses of various electrical conduction mechanisms showed that optimized electron scattering behavior, reduced hopping distance, energy and theoretical Curie temperature collectively enhance the temperature coefficient of resistivity (TCR) of LCMO films under optimal P s . The TCR of the LCMO films reached a maximum value (31.64 % K- 1 ) at P s = 18 min. These findings offer valuable insights into the main electrical conduction mechanisms in both metallic and semiconducting phases, providing a deeper understanding of the underlying physical processes and offering experimental guidance for optimizing the electrical transport properties of perovskite films.