Designer Color‐Tunable NIR‐Reflective Cool Pigments in the Ternary Vanadate Phenacite‐Inverse Spinel Phase Regime

Abstract Li‐containing ternary vanadates are known for their remarkable structural diversity and tunable physical properties, making them attractive for advanced functional applications. In this study, a systematic investigation of Co 2+ and Ni 2+ ‐doped LiZnVO 4 (LZVO) is presented to elucidate their structural transitions, optical behavior, and potential for energy‐efficient coating technologies. A clear miscibility gap is observed in intermediate compositions, indicating limited solid solubility between the two end members. The local lithium environments are probed using magic angle spinning 7 Li and 51 V solid‐state NMR spectroscopy, providing direct evidence for the incorporation of the two paramagnetic dopant ions into the crystal lattice. At low dopant concentrations, the 7 Li isotropic peak intensity increases due to paramagnetic relaxation enhancement, whereas higher concentrations lead to characteristic peak broadening. CIELAB color space shows systematic color tuning with increasing dopant concentration: green → brown → black for Co‐doping and light greenish yellow → yellow → brown for Ni‐doping. Importantly, the doped LZVO‐0.02Ni and LZVO‐0.02Co compositions exhibit high NIR solar reflectance of 85.7% and 65.2% respectively, in the wavelength range 700–2200 nm, enabling effective solar heat management. The combination of phase‐selective doping, tunable color properties, and strong NIR solar reflectivity positions these materials as promising candidates for next‐generation cool pigments.