Sustainable inorganic cool pigments based on Tungsten doped FeZrO3.5

r0.8W0.2O3.5 FeZr0.6W0.4O3.5 FeZrWO3.5 High near-infrared reflecting inorganic nano pigments (FeZr1-xMxO3.5; where M = tungsten (W6+) and x ranges from 0 to 0.4) based on Iron zirconium doped with W6+ was synthesised by a novel citric acid assisted Sol-Gel route followed by calcination. The pigment and composite samples were characterised by TG-DTA, XRD and UV–Vis–NIR spectrophotometer. The results showed that the pigments crystallised completely at 600°C with particle size less than 50 nm. The substitution of W6+ for Zr4+ in FeZrO3.5 induced the absorption in the 480-580 nm region. The red colour of the FeZrO3.5 is found to be changed to purple upon doping 10% tungsten and blue-green upon 20% doping of tungsten. The near-infrared reflectance varied with 45-53%, varying the W6+ content. Thus, these pigments can be excellent candidates for use as cool pigments in walls or roofs of buildings.