New insight into the coloration mechanism and synthesis of ultrafine Pr‐ZrSiO₄ yellow pigments

Abstract

It is of particular significance to unveil the authentic coloration mechanism of the multivalent praseodymium colored ZrSiO4 yellow pigments for advanced decoration applications. We herein adopted a facile strategy to modulate the fluorine‐assisted zircon crystallization and thereby obtained ultrafine Pr‐ZrSiO4 yellow pigments, which have a remarkably narrow size distribution and average diameters within 250–400 nm. By virtue of some cogent combinative spectra of reflection, absorption, excitation, and emission from three types of elaborately‐designed H2‐, air‐, and O2‐based pigments, the coloration mechanism for the Pr‐colored zircon was systematically unveiled: both Pr4+ and Pr3+ coexist invariably in the pigments, while the former contributes primarily to the ligand‐to‐metal charge transfer from O2p to Pr(IV)4f for the blue–violet absorption to generate the yellow hue, and the latter is inclined to discolor the pigments. Therefore, an oxidizing atmosphere is preferable to produce brilliant Pr‐ZrSiO4 pigments with enhanced chromatic properties. The stark spectroscopic distinctions between the wide‐band absorption from the nonluminescent tetravalency and the narrow‐band absorption from the luminescent trivalency can expand our understanding to the rare‐earth‐based inorganic pigments.