Research on new ceramic dyes is addressed to obtain best pigmenting materials in
order to reach higher thermal stability (e.g. for porcelainised stoneware) than classical
pigments, higher chemical stability towards the coloured matrix or low toxicity in order to
satisfy health and environmental requirements. The earlier developments on the research in
new ceramic pigments based on new crystal structures (e.g. perovskite, hexaaluminates,
fergusonite, pseudobrookite …), new chromophores (e.g. ruthenium, bismuth and rare earth
ions), or new methods of preparation are discussed in this communication.
Solid solutions Ca(D x M 1Àx )O 3 (M = Ti, Zr and D = Fe,Cr), have been studied as ceramic pigment in conventional ceramic glazes using 0.5 mol/ mol of NH 4 Cl as flux agent by solid state reaction and by ammonia coprecipitation route. Ca(Cr x Ti 1Àx )O 3 compositions obtained without addition of NH 4 Cl as mineralizer, produce pink color in glazes at low x but CaCrO 4 crystallizes when x increases, producing undesired green colors. The crystallization of chromates can be avoided using NH 4 Cl as mineralizer, giving a complete solid solution that produce pink color in glazes at low x and dark blue shades at high x. Coprecipitated sample produce blue colors at low x and at low temperature than ceramic sample (1000 8C instead 1200 8C for CE sample). Cr 4+ ion acts as red chromophore, but at higher x values (blue samples) Cr 3+ ion entrance affects the color. Ca(Fe x Ti 1Àx )O 3 system crystallizes perovskite CaTiO 3 and pseudobrookite Fe 2 TiO 5 together with rutile as residual crystalline phase, glazed samples change from a yellow to a pink color associated to the increase of pseudobrookite with firing temperature. Ca(Fe x Ti 1Àx )O 3 and Ca(Cr x Zr 1Àx )O 3 systems crystallize perovskite CaZrO 3 and zirconia (ZrO 2 ) in both monoclinic and cubic polymorphs, but iron or chromium oxides are not detected in the powders. Coprecipitated sample stabilises cubic form. The solid solution is not reached completely in these samples and is not stable in glazes. #
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.