Synthesis of Nd sub(2)Si sub(2)O sub(7) ceramic pigment with LiCl as a mineralizer and its color property

This paper was to synthesize a ceramic pigment of tetragonal Nd sub(2)Si sub(2)O sub(7) by the Pechini sol-gel method and subsequent thermal treatment. The crystallization processes of the pigment precursors with and without LiCl of 5 wt.% as a mineralizer were investigated by X-ray diffraction and thermogravimetry-differential thermal analysis, respectively. The results show that LiCl can promote the formation of monoclinic Nd sub(2)Si sub(2)O sub(7) transient phase at a lower heat-treated temperature. The color properties of pigment samples were measured in color space CIE L*a*b* under different standard illuminants (i.e., solar-light D sub(65), incandescent light A, cool white fluorescent lamp F2, and three-band fluorescent lamp F11). The color changes of Nd sub(2)Si sub(2)O sub(7) pigment under different illuminants were also characterized quantitatively via the color difference analysis. The maximum value of the color difference between D sub(65) and F11 can reach 12.65, implying that Nd sub(2)Si sub(2)O sub(7) pigment could be used as a functional ceramic pigment with "allochroic effect". In addition, the mechanism of color change under various light sources was also discussed.