Sol-Gel Combustion-Derived CoCuMnOx Spinels as Pigment for Spectrally Selective Paints

In this work, sol-gel combustion synthesis of spinel CoCuMnOx was reported. X-ray diffraction (XRD) and Fourier transformation infrared spectroscopy (FTIR) techniques were used to study the reaction processes. The as-synthesized spinel CoCuMnOx was further characterized by XRD, X-ray photoelectron spectroscopy, and field-emission scanning electron microscopy. The CoCuMnOx powders with a deep black hue were then used as solar energy-absorbing additive to make a novel kind of spectrally selective paint coatings. The solar absorptance (alpha(s)) and the thermal emittance (epsilon(T)) of the coatings were determined from the corresponding diffuse reflectance spectra in the 0.3-20 mu m range. The optimum selective sample exhibited values of alpha(s)=0.928 and epsilon(100)=0.198. Besides ideal optical properties, the coatings also show excellent long-term stability, which is confirmed by results of accelerated tests established by IEA-SHC Task X, indicating that they could be a good alternative to the materials present today in the market.