Preparation and modification of inverse opal zirconia pigment

Inverse opal zirconia pigment prepared by traditional process has the disadvantages of low color saturation and variegated color which restrict its further application. In this work, the inverse opal zirconia pigment was prepared by colloidal crystal template fabricated using polystyrene microspheres with particle size of 340 ? 10 nm as raw material and further modified by sintering at 600 ?C for 2 h with heating rate of 2 ?C/min in an atmosphere tube of 0.8 L min-1 nitrogen flow. The morphology, phase crystallinity and color performance of the inverse opal zirconia pigment before and after modification were characterized in detail and the modified mechanism was investigated. The results showed that morphology of the inverse opal zirconia pigment before modification was basically a highly ordered porous structure, the phase was relatively pure, and the overall appearance was variegated color. Some parts of the samples exhibited low color saturation and different areas showed various colors, indicating that the samples had certain angle dependence. After modification, the samples showed bigger-area single blue-green color, suggesting that the color saturation was significantly improved and the angle dependence was reduced evidently. The mechanism for modification was that the zirconia precursor and polystyrene templates were carbonized when sintered in nitrogen atmosphere. The generated in-situ carbon remained in the samples and absorbed the tray background light, which significantly suppressed the multiple scattering of structural defects.