The effect of B site doping on infrared emissivity of lanthanum manganites La0.8Sr0.2Mn1−B O3 (B = Ti or Cu)

The lanthanum manganites La0.8Sr0.2Mn1−xBxO3 (B = Ti or Cu, 0 ≤ x ≤ 0.4) were prepared by standard solid-state reaction method. The structure, infrared absorption, electron spin resonance (ESR) and infrared normal emissivity (ɛN) in the 8–14 μm waveband of the samples were systematically investigated. The samples are perovskite with distorted rhombohedral structure. Compared to x = 0 sample with ɛN value 0.693, infrared absorption occurred in the 8–14 μm waveband leads to high emissivity value of the B site doping samples (ɛTi = 0.912 and ɛCu = 0.894), and the ɛN decreases slightly with increasing doping level due to decreasing transition probability indicated by ESR results. The ɛN changes slightly in the temperature range 293–373 K, from 0.9 to 0.882 for Ti doping and from 0.886 to 0.879 for Cu doping, owing to the weakening of the double-exchange interaction between Mn3+ and Mn4+.