Near-infrared reflecting blue inorganic nano-pigment based on cobalt aluminate spinel via combustion synthesis method

Abstract

CoAl2O4 nanoparticles as a high NIR solar reflectance inorganic pigment was successfully prepared by combustion synthesis using glycine, malonic acid dihydrazide as a simple fuel and mixture of them with different molar ratio, following by annealing in temperature range of 400–1000 °C. As-prepared and annealed products characterized by using various tools such as TGA/DTA, XRD, HRTEM, EDX, DRS, FTIR. The color of products was studied using CIE1978 L∗a∗b∗ colorimetric method. In addition, the solar reflectance was determined by using (JIS) standard k5602-2008. The obtained results referred that powder product exhibits a high solar reflectance with value 38.18% in UV–Visible region, 51.82% in NIR region and total solar reflectance was 43.7% and the optical band gap of products was determined. The blue pigments on glaze give a maximum NIR solar reflectance in range of 61.3–69.08%. These results demonstrate the prepared products are a suitable as cool blue inorganic pigments on glaze.