Application of LnCrTeO6 oxides as new ceramic pigments of the type "green chromium"

Abstract

The family of green mixed oxides LnCrTeO6 (Ln = La, Nd, Gd, Dy, Er, Tm and Yb) was investigated as potential new green ceramic pigments. Prior to enamelling, they were fully characterized by XRD analysis and FTIR spectroscopy. The materials were tested by enamelling with transparent and opaque glazes, applied for single and double firing. The chromatic qualities of all the formulations, obtained in the thermal range 850-1000°C, were evaluated. The colour performance is fairly maintained at 1000°C, in the transparent frit, and a lighter green hue is achieved in the opaque frit. In presence of a PbO-containing frit, a dark green yellowish shade is obtained. The colorimetric parameters a and b are within the range of typical pigments based on Cr2O3 in silicate and aluminate glazes. The homogeneity of the enamels was confirmed by SEM-EDX microscopy. These materials are promising for ceramic applications since a low amount of Cr-pigment would be necessary to achieve intense green coloration.