The design of vanadium–titanium co-doped zircon pigments and color mechanism

The current study aims to design and synthesize a set of vanadium–titanium (V-Ti) co-doped zircon pigments using solid-state routes. It also evaluates the relationships that exist between their structure and properties. To execute this, we employed a multi-technique approach by combining high-resolution XRPD through Rietveld refinement, UV–Vis–NIR electronic absorption spectroscopy (EAS), electron paramagnetic resonance (EPR) spectroscopy, particle-size and morphology examinations, and Angular Overlap Model (AOM) estimations. The XRPD refinements indicate that zircon is the primary phase, accompanied by minor traces of TiO₂ and baddeleyite. Moreover, Lattice parameters indicate anisotropic expansion predominantly along the c-axis. Both EPR data and AOM modeling consistently confirmed that axially distorted V4+ centers are preferably positioned at the interstitial 16 g area. EAS displays broad absorption bands throughout the visible spectrum, giving it the features of a turquoise hue; modifications in absorption minima correspond to CIE-Lab colorimetric parameters. As the V content increases, Microstructural measurements (PSD/SEM) reveal a moderate refinement of the grain, leading to color uniformity. Collectively, the chromophore mechanism is elucidated by convergent structural, spectroscopic, and modeling evidence, which drives the interstitial V4+ anisotropic lattice reaction and leads to the development of a turquoise hue, offering applicable guidelines for eco-friendly, industrially feasible zircon pigments.