The Dugganite Structure as a Host for New Colored Compounds and for Oxygen Evolution Studies

A family compounds with the general formula A₃BC₃D₂O₁₄ (A = Pb, Ba, Sr; B = Te, Sb; C = Al, Ga, Fe, Zn, Mg, Co, Ni, Cu; D = P, V, As, Si, Ge) stabilized in the dugganite structure has been prepared and characterized. The transition metal ions substituted at the tetrahedral sites in place of Zn²⁺ ions, gave rise to brightly colored compounds. The origin of colors in the compounds were understood based on the allowed d-d transitions and possible metal-to-metal charge transfer (MMCT) transitions involving the different transition elements. The white compounds exhibited good near infrared (NIR) reflectivity as well as deep UV-cut off (85-90%), which indicates possible use as UV-NLO materials. The compounds exhibited reasonable second harmonic generation (SHG) activity with values that are 3-5 times higher than KDP. The dielectric studies indicated reasonable values for the dielectric constant with low dielectric loss. The oxygen evolution reaction (OER) studies on Pb₃TeCo₃V₂O₁₄ and Pb₃Te(Co₂Fe)(VSi)O₁₄, exhibited good OER behavior in alkaline medium with long-term stability. The change in the band gap values for the transition metal substituted compounds were understood through density functional theory calculations, which support the findings of the experimental investigations. The present study clearly indicates that it is profitable to explore mineral structures as hosts toward new colored compounds, substitution of transition elements that result not only in new and also for application as electrocatalysts through careful band engineering.