Temperature dependence of infrared emissivity properties of (La0.8Sr0.2)1−xMnO3

Non-stoichiometric compounds of (La_0.8Sr_0.2)_1−xMnO₃ (0.1 ≤ x ≤ 0.4) were prepared by standard solid-state reaction method. The structure, infrared absorption and normal emissivity (_N) properties of the compounds were systematically investigated. The X-ray powder diffraction (XRD) results indicate that the structure of the samples is distorted rhombohedral but not cubic. The mechanism of new infrared absorption occurring around 719–922 cm⁻¹ is proposed. The _N of the samples in the 8–14 μm waveband increases with increasing temperature and changes significantly in the temperature range 288–313 K due to the metal-insulator transition. Moreover, the _N value for x = 0.2 is higher than that for the other samples, owing to two strong infrared absorption peaks at 719 cm⁻¹ and 856 cm⁻¹. The _N has no drastic change with increasing temperature in the 3–5 μm waveband.