Radiative and Optical Properties of La1−xSrxMnO3 (0≤x≤0.4) in the Vicinity of Metal–Insulator Transition Temperatures from 173 to 413K

Radiative and optical properties of polycrystalline La1−xSrxMnO3 (0 [ x [ 0.4) in the vicinity of the metal–insulator transition are preseInted.The temperature dependence of the total hemispherical emittance eH of La1−xSrxMnO3 was measured by the calorimetric method in the temperature range from 173 to 413 K.It was confirmed that eH showed unexpected variation as a result of changes in the hole concentration (x).Especially in the case of La0.825Sr0.175MnO3 , eH remains high above the transition temperature TC due to insulator-like behavior; on the other hand, it decreases sharply below TC because of metallic behavior. The spectral reflectance was measured by FT-IR in the wavelength range of 0.25 to 100 mm at room temperature.The optical constants were calculated by Kramers–Kronig analysis of the spectral reflectance data.An insulator-like character of the optical properties appears at lower Sr2+ doping levels while a metallic one exists at higher Sr2+ doping levels.