Novel Environmentally Friendly Blue Pigments Based on Na4Cu(PO4)(2)

Novel environmentally friendly blue pigments, Na4Cu1-x-Mg-x(PO4)(2) (0 <= x <= 0.25), were synthesized. By doping Mg2+ with lower electronegativity into Cu2+ sites, the crystal lattice was distorted, which strongly affects the charge transfer from O2- to Cu2+ and the d-d transition of Cu2+ In the series of Na4Cu1-xMgx(PO4)(2), the Na4Cu0.85Mg0.15(PO4)(2) solid showed a vivid blue hue with a blueness value (-b*) of 38.2 in the CIE L *a*b* system.