Optical characteristics and application of cobalt/nickel doped SrZn2(PO4)2 blue-violet and violet inorganic pigment powders

• Co/Ni doped SrZn 2 (PO 4 ) 2 solid solutions were synthesized via solid state method. • The resulting pigments exhibit blue-violet and violet hues. • These materials demonstrate outstanding thermal stability. • Their colors arise from d-d transitions of Co 2+ /Ni 2+ in tetrahedral sites. • The pigments show excellent compatibility for PMMA plastic coloration. Blue-violet and violet inorganic pigments, derived from SrZn 2- x Co x (PO 4 ) 2 (0 ≤ x ≤ 1) and SrZn 2- x Ni x (PO 4 ) 2 (0 ≤ x ≤ 0.5) solid solutions, were successfully synthesized via a solid-state reaction. The structure, color, optical properties, and potential applications of the synthesized pigments were systematically characterized. All pigments crystallized in a single-phase structure. Rietveld refinement analysis confirmed the successful substitution of Zn 2+ by Co 2+ /Ni 2+ in the lattice. Based on the XPS and UV–Vis–NIR analyses revealed that the coloration of Co 2+ /Ni 2+ doped SrZn 2 (PO 4 ) 2 originates from d-d electronic transitions in a tetrahedral coordination environment. Compared to commercial purple pigments, such as Co 3 (PO 4 ) 2 and NH 4 MnP 2 O 7 , the synthesized pigments exhibit superior thermal stability and require lower cobalt or nickel doping levels. Furthermore, 2 wt% of these pigments were incorporated into poly(methyl methacrylate) (PMMA) plastic to form blue-violet and violet composites, whose color and optical properties were systematically analyzed.