YIn0.9Mn0.1O3–ZnO NIR reflective nano-pigment exhibiting three different colors: Ochre, cyan blue, and deep blue

A set of NIR reflective nano-pigments displaying YIn0.9Mn0.1O3–ZnO stoichiometry was synthesized by sol-gel route. The dried gel precursor was calcined at different temperatures for 2h (550 °C, 650 °C, 750 °C, 800 °C, and 850 °C), observing the formation of three ochre pigments and two different blue shades. Precursors and final calcined pigments were characterized by thermogravimetry (TGA) and differential scanning calorimetry (DSC) analysis to monitor the NIR reflective pigments production and their thermal resistance. Fourier transform infrared (FT-IR) spectra were collected to know chemical changes obtained by calcination process. Crystalline phases and morphology of nano-pigments were studied using X-ray diffraction (XRD) and scanning transmission electron microscope (STEM) observation, respectively. The synthesized pigments showed near infrared (NIR) reflectance ability. The final color was evaluated according to CIE-1976L*a*b* method obtaining a standard identification of each color.