Synthesis and chromatic properties of novel eco-friendly green pigments PrxCa2-xAl2SiO7 (0 < x ≤ 0.1)

Novel eco-friendly green pigments, Pr x Ca 2 -x Al 2 SiO 7 (0 < x ≤ 0.1) were synthesized via a solid-state method using Pr 6 O 11 as the coloring oxide and Ca 2 Al 2 SiO 7 as the base material. The results reveal that praseodymium (Pr) ions dissolved into the Ca 2 Al 2 SiO 7 lattice, with the green coloration primarily attributed to Pr 3+ in the lattice. The solid solution was influenced by both temperature and the amount of Pr 6 O 11 introduced. A bright green pigment with composition Pr x Ca 2 -x Al 2 SiO 7 ( x = 0.08) was obtained by maintaining the material at 1350°C for 1.5 h, yielding chromatic parameters L*: 78.29, a*: -18.37 and b*: 27.51. Pr 3+ , responsible for coloration, are retained in an octahedral coordination environment by substituting Ca 2+ in the Ca 2 Al 2 SiO 7 lattice, while Pr 4+ are converted to Pr 3+ when the temperature exceeds 1323K. The newly synthesized pigment is non-toxic, harmless, and exhibits remarkable thermal stability, its successful application to biscuit ceramics highlights its potential as a sustainable and eco-friendly pigment for the ceramics industry.