Synthesis of Nd2Si2O7 ceramic pigment with LiCl as a mineralizer and its color property

• Nd2Si2O7 ceramic pigment with LiCl as a mineralizer was synthesized.
• The color property of the Nd2Si2O7 pigment was characterized using the CIE L*a*b* system.
• The Nd2Si2O7 pigment presented different colors under various illuminants.
• The maximum color difference value between D65 and F11 reached 12.65.
• The mechanism of color change under various light sources was discussed.

This paper was to synthesize a ceramic pigment of tetragonal Nd2Si2O7 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 Nd2Si2O7 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 D65, incandescent light A, cool white fluorescent lamp F2, and three-band fluorescent lamp F11). The color changes of Nd2Si2O7 pigment under different illuminants were also characterized quantitatively via the color difference analysis. The maximum value of the color difference between D65 and F11 can reach 12.65, implying that Nd2Si2O7 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.