Effect of mechanical activation on solid-state synthesis process of neodymium disilicate ceramic pigment

The effect of mechanical activation of precursors ground in a high-energy density stirred bead mill on the synthesis of Nd2Si2O7 powders was investigated. The reaction of precursors after the mechanical treatment at different milling time was analyzed by laser particles size analysis, thermogravimetry and differential thermal analysis (TG-DTA), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results reveal that the precursors without grinding and fired at 1200 °C cannot form the Nd2Si2O7 phase. Nd2Si2O7 can be formed at 986.9 °C when the precursors are ground for 3.0 h. To further clarify the effect of mechanical activation, two raw materials (i.e., SiO2 and Nd2O3) were pre-treated by different methods. The raw materials mixed and subsequently ground is conducive to decreasing the temperature of forming pure Nd2Si2O7 phase. The results indicate that the mechanical activation favors the promotion of the crystal growth of Nd2Si2O7. In addition, the color properties of the synthesized Nd2Si2O7 powders were also evaluated by reflection differential colorimetry. It is indicated that Nd2Si2O7 powders that possess a high-temperature stability can be used as a ceramic pigment.