A novel inorganic violet pigment based on zinc niobate

Abstract

(Zn_1−xCo_x)₃Nb₂O₈ (0 ≤ x ≤ 0.50) samples were synthesized as novel inorganic violet pigments by a conventional solid-state reaction method, and the powders obtained were characterized by using X-ray powder diffraction (XRD), ultraviolet and visible (UV-Vis) diffuse reflectance spectroscopy, and L*a*b*Ch° chromatic coordinates defined by the Commission Internationale de l’Éclairage (CIE). The (Zn_1−xCo_x)₃Nb₂O₈ (0 ≤ x ≤ 0.20) pigments were obtained in a single phase form. The Co atoms introduced into the lattice occupied both octahedral and tetrahedral sites, and the amount of Co in both sites was almost the same. Considering the Laporte rule and the results of the Rietveld analysis, optical absorption was observed around 450 and 530–600 nm in the Co²⁺-doped samples, which was mainly due to the d–d transition of Co²⁺ in the tetrahedral site. The absorption intensity increased with increasing the Co²⁺ concentration. The most vibrant violet color was obtained with (Zn_0.80Co_0.20)₃Nb₂O₈.