Mixed manganese spinel oxides: optical properties in the infrared range

Spinel oxides in manganite family are studied in terms of optical properties in the infrared range (3–12 lm). The reflectivity is measured on sintered pellets. The complex refractive index is estimated by fitting hemispherical directional reflectance in both polarizations, perpendicular and parallel. The influence of different metallic cations (Ni, Co, Fe, Cu) is compared. In particular, in the case of manganese nickel copper oxides, the impact of variations in copper and nickel contents is evaluated. Cationic distribution is determined and correlated to the optical characteristics. These materials, usually used for NTC thermistor applications, are investigated for IR charges in coating