Infrared thermochromic behaviour of a composite Sm0.65Ca0.35MnO3–poly(styrene-co-acrylonitrile) film

Samarium calcium perovskite manganite Sm0.65Ca0.35MnO3 was dispersed homogeneously in a solution of poly(styrene-co-acrylonitrile). A thin film was deposited on (100) oriented silicon substrate by spin-coating and the optical thermochromic behaviour in the infrared range was studied. In the wavelength range 8–14 µm, the optical transmittance of the thermochromic composite coating exhibited a large variation between 173 and 343 K due to a semiconductor–metal first-order transition at Tc = 250 K. The thermochromic behaviour of the composite coatings was optimized. The contrast in the transmittance first increased with pigment content, then reached a maximum value