Effect of doping-induced MnO6 distortion on the phase transition temperature and emissivity of LaMnO3-based materials

Abstract

Large variable emissivity materials play a key role in smart thermal control. However, conventional variable emissivity materials have limitations, including insufficient variability and unclear understanding of how phase-change temperature and emissivity variation relates. In this study, LaMnO₃-based (ABO₃) perovskite materials doped with ions of varying radii were prepared. Among them, La_0.7Ba_0.2Cd_0.1MnO₃ showed a variable emissivity of 0.467 and a Curie temperature of 290 K. Combining experimental studies with density functional theory calculation reveals that the mechanism for tuning the Curie temperature is linked to the displacement of A-site ions, resulting from the distortion of the MnO₆ octahedron. Besides, the variable emissivity mechanism is explained by the densities of states, which decrease as Mn-O bond strength increases. This work explores the mechanism of phase transition temperature and emissivity changes from an intrinsic crystal structural perspective and will provide theoretical foundations for improving variable emissivity properties of smart thermal control systems.