Synthesis of new red coloured ceramic pigments by Pechini method

Various garnet solid solutions within the structure of the yttrium aluminium garnet, Y3Al5O12 (YAG) were sinthesized via Pechini and the possibility for the modification of the crystal field intensity acting on the chromophore Cr(III) ion by means of substitution with divalent (Mn(II) and Mg(II)) and tetravalent (Ce(IV), Zr(IV) and Sn(IV)) cations was studied. The results obtained indicate that the crystal field can not be intensified through the introduction of divalent ions since they stabilize the Gr(IV) ion which probably expands the structure by inducing distortions in it. The introduction of tetravalent ions makes possible the intensification of the crystal field acting on the chromium and the change of the typical green colour of Cr(III) in a week field to red which is typical for the same in strong field. However, the structural studies carried our by X-ray diffraction show that together with the garnet fase Y0 ,15Zr0,85O1,93 and Y2Sn2O7 are formed, the latter having pyrochlore structure. It was demonstarted that the introduction of Cr(III) in the mantioned pyrochlore structure results in the formation of a red- violet pigment. Finally, the sinthesized fases were checked as pigments using an industrial transparent boron containing frit. The tin containing pigments demonstrated good pigmenting ability and stability at 1080 degreesC.