Advances in Engineering Advances in Engineering features breaking research judged by Advances in Engineering advisory team to be of key importance in the Engineering field. Papers are selected from over 10,000 published each week from most peer reviewed journals.
Ceramics International, Volume 40, Issue 1, Part A, January 2014, Pages 611-617.
Griselda X. Gayo, Franco Troncoso, Araceli E. Lavat.
Facultad de Ingeniería, Universidad Nacional del Centro, Av. Del Valle 5737, B7400JWI Olavarría, Argentina.
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 firings. 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 the 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.
Additional information:
The electronic spectra of glazes (a) transparent and (b) opaque frits containing LnCrTeO6 pigments are depicted in the figure. Two main broad absorption bands centred approximately at 600 nm and in the range 400-475 nm are observed. These bands are assigned to the electronic transitions: ν1= 4A2g(4F)→ 4T1g(4F) and ν2= 4A2g(4F)→ 4T2g(4F) of Cr(III) in octahedral distorted site, respectively.
The presence of a region of minimum absorbance, between these two bands, located at 500-550 nm, demonstrates that the visible green light is mostly transmitted by the Cr(III) chromophore cation in these ceramic glazes.
