Mg添加による(Al, Cr)₂O₃顔料の色調変化

抄録

Addition of Mg into (Al, Cr)₂O₃ pigments significantly varied their colors. The Mg-added pigments consisted of (Al, Cr)₂O₃ corundum phase (C-phase) and Mg(Al, Cr)₂O₄ spinel phase (S-phase). In order to obtain data for the evaluation of the Cr contents in the C-and S-phases, (Al_1-xCr_x)₂O₃ corundum and Mg (Al_1-xCr_x)₂O₄ spinel both with x ranging from 0 to 1 were synthesized, and their lattice constants were measured by the XRD method. Lattice constants of the C-phase in the pigments prepared from (0.9_-x)mol Al₂O₃, 0.1mol Cr₂O₃ and x mol MgCO₃ were independent of the Mg content, and the Cr concentration of the C-phase in each pigment was determined to be 10mol%. On the other hand, a lattice constant of the S-phase decreased with the increase in the Mg content. Using the lattice constant data of the synthesized spinel and corundum, it was shown that the Cr content of the S-phase decreased with the increase in the Mg content. It was concluded that the color variations caused by the Mg addition into (Al, Cr)₂O₃ pigments were attributable to changes of the Cr content of the S-phase.