Research on Tin-Chrome Spinel Pigments containing Co<sup>2+</sup> and Ni<sup>2+</sup> Ions

Abstract

For the purpose of researching into the formation and the color development of tinchrome single spinels, the gradual substitution according to the following formula was carried out for each tin spinel.Mg2+(Zn2+)+Sn4+→←2Cr3+Thus, MgO-SnO2-Cr2O3, ZnO-SnO2-Cr2O3, CoO-MgO-SnO2-Cr2O3, CoO-ZnO-SnO2-Cr2O3, NiO-MgO-SnO2-Cr2O3, NiO-ZnO-SnO2-Cr2O3, CoO-NiO-MgO-SnO2-Cr2O3 and CoO-NiO-ZnO-SnO2-Cr2O3 systems were investigated.On samples prepared by calcining the oxide mixtures at 1350°C for 1 hour, the X-ray analysis and the measurement of reflectance between 400-760mμ were carried out, and color glaze test was then made. The results were summarized as follows.(1) Continuous solid solutions of tin and chrome spinel and obedience to Vegard's law except a few instances were confirmed by X-ray analysis. Consequently, single spinels of the color ranging from blue to bluish green or from yellowish green to dark green were obtained.(2) Deviation from Vegard's law was observed in CoO-ZnO-SnO2-Cr2O3 and NiO-ZnO-SnO2-Cr2O3 systems, owing to the strong coordination preference of Cr3+, Ni2+ and Zn2+ ions.(3) As the amount of Cr3+ ions increased, the absorption of Cr3+ ions shifted towards violet region, owing to the construction of octahedral interstices. On the contrary, absorption of Co2+ ions did not shift, because the space of tetrahedral interstices were maintained constant.(4) Accoding the results of color glaze test, spinels with the composition in Cr3+ rich region were appreciated to be applicable for pottery.