Green colored nano-pigments derived from Y2BaCuO5: NIR reflective coatings

• A green colored nano-pigment Y2BaCuO5 with impressive NIR reflectance (61% at 1100 nm) was developed.
• The UV–vis spectrum exhibits an intense d–d transition associated with CuO5 chromophore between 2.1 and 2.5 eV.
• Developed bright green pigments superior to that of commercially available chromium based pigments.
• The potential utility of the nano-pigments as “Cool Pigments” was demonstrated by coating on to cement slab and PVC.

A green colored nano-pigment Y2BaCuO5 with impressive near infra-red (NIR) reflectance (61% at 1100 nm) was synthesized by a nano-emulsion method. The developed nano-crystalline powders were characterized by X-ray diffraction (XRD), Transmission electron microscopy (TEM), UV–vis–NIR diffuse reflectance spectroscopy and CIE-L*a*b* 1976 color scales. The XRD and Rietveld analyses of the designed pigment powders reveal the orthorhombic crystal structure for Y2BaCuO5, where yttrium is coordinated by seven oxygen atoms with the local symmetry of a distorted trigonal prism, barium is coordinated by eleven oxygen atoms, and the coordination polyhedron of copper is a distorted square pyramid [CuO5]. The UV–vis spectrum of the nano-pigment exhibits an intense d–d transition associated with CuO5 chromophore between 2.1 and 2.5 eV in the visible domain. Therefore, a green color has been displayed by the developed nano-pigment. The potential utility of the nano-pigments as “Cool Pigments” was demonstrated by coating on to a building roofing material like cement slab and PVC coatings.

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