Exploring LiZnNbO4 as a Host for New Colored Compounds: Synthesis, Structure, and Material Properties of NbZn1-x Mx LiO4 (M=Mn, Co, Ni, Fe) and Nb1-ySby Zn1-x Mx LiO4 (M=Co, Ni)

The non - centrosymmetric tetragonal inverse spinel structure of LiZnNbO4 has been explored with a view to prepare new colored compounds. The substitution of Co2+, Ni2+, Fe2+, Mn2+, and Cu2+ ions were attempted in the place of Zn2+ ions and Sb5+ ions in place of Nb5+ ions. The studies indicated that 0.75 Zn2+ ions in LiZnNbO4 can be replaced by Co2+ ions and 0.5 Zn2+ ions in LiZnNb0.5Sb0.5O4 compound. The substitution of Co2+ ions gives rise to different shades of blue color in Li(Zn1-xCox)NbO4 compounds and from ink blue to blue-green color in Li(Zn1-xCox)(Nb0.5Sb0.5)O-4 compounds. The different colors observed in the present study were explained by the traditional allowed d-d transitions as well as the metal-to-metal charge transfer (MMCT) transitions involving Nb5+ (4d(0)) ions and partially filled 3d electrons. The SHG studies indicate that the prepared compounds are SHG active. All the compounds exhibit reasonable dielectric behavior with low loss. The XPS studies confirm the oxidation states of the different substituted ions. Raman studies indicate variations in the bands due to the substitutions in the parent LiZnNbO4 phase. Magnetic studies on the Co2+ ions substituted compounds suggest antiferromagnetic behavior.