Scheelite and Zircon

The subject of this book is the analysis of the performance in ceramics of scheelite (CaWO4) and zircon (ZrSiO4). The aesthetics of glazed ceramics and paints depends to a large extent on the so-called opacifiers that give them brightness and pigments that give them colour. At present, zircon ZrSiO4 is the main opacifier of industrial ceramic glazes and the base of a widely-used pigment palette (cyan of vanadium in zircon, magenta of hematite in zircon and yellow of praseodymium in zircon). Likewise, scheelite CaWO4 can be used as a good opacifier by addition to glazes and is the basis of another family of inorganic pigments. These pigments are analysed from the perspective of their cooling capacity of buildings and urban environments, associated with their high reflectance of solar NIR radiation (700-2500 nm), as well as a certain photocatalytic capacity over organic substrates and NOx; therefore, surfaces with these pigments show a certain air purification capacity producing cleaner and cooler environments, allowing a saving in the use of air conditioning and a moderation of the so-called urban heat island effect. In short, the brightness, colour and NIR reflectance for cool surfaces in paints and ceramics using scheelite and zircon chemistry are discussed.