Study of the role of praseodymium and iron in an environment-friendly reddish orange pigment based on Fe doped Pr2Zr2O7: A multifunctional material

Abstract New environment-friendly reddish orange ceramic pigments based on the general formula Pr2Zr2-xFexO7-δ (x = 0, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared by the coprecipitation method and fired at 1200 °C. X-Ray Diffraction (XRD) showed a pyrochlore phase in all compositions, whereas Raman spectroscopy revealed the presence of a fluorite phase together with pyrochlore. Although the pyrochlore phase is the main phase, the amount of fluorite phase slightly increases with iron content. UV/Vis absorption measurements, photoluminescence and XPS were used to determine the oxidation state of praseodymium and iron, and a possible redox mechanism was proposed. A mixture of the oxidation states Pr(IV)/Pr(III) and Fe(II)/Fe(III) is present in all samples. All compositions offered good stability after mixing the powders with glass, polymer and paint. The color of the final products in powder and after mixing them with the different media was determined by CIEL*a*b* chromatic coordinates and CIEL*C*Ho parameters. Concentrations with x = 0.15 and 0.20 have the highest values of a* and lowest values of Ho in all media and, therefore, the best reddish hue. The good stability and the color of this pigment in siloxane paint, as well as the high value of NIR reflectance, allows its application as a cool pigment, thus making this material a good candidate as an environment-friendly reddish orange pigment with multifunctional applications.