Development of a novel nontoxic vivid violet inorganic pigment – Mn³⁺-doped LaAlGe₂O₇

Novel nontoxic LaAl_1-xMn_xGe₂O₇ (0.01 ≤ x ≤ 0.20) violet pigments were synthesized through a conventional solid-state reaction. The crystal structures, optical properties, and color properties of these pigments were investigated. The LaAl_1-xMn_xGe₂O₇ (0.01 ≤ x ≤ 0.20) pigments prepared in the present study show excellent potential as environmentally friendly inorganic violet pigments. These pigments exhibit a strong optical absorption in the yellow-red light region due to the Mn³⁺ d–d transitions, which is the origin of the violet color. Among the obtained LaAl_1-xMn_xGe₂O₇ (0.01 ≤ x ≤ 0.20) pigments, LaAl_0.90Mn_0.10Ge₂O₇ showed the most vivid violet color and the L*, a*, and b* values are 50.8, 18.0, and −29.7, respectively, values greater than those of a commercial cobalt violet pigment (Co₃(PO₄)₂; L* = 46, a* = 33, b* = −32). Because the LaAl_0.90Mn_0.10Ge₂O₇ pigment is composed of nontoxic elements, this pigment can be an effective alternative to currently used commercial violet pigments.