Urban heat islands have become a global issue, as they severely impact several key factors, including elevated energy consumption, increased air pollution and greenhouse gas emissions, compromised human health and comfort, and reduced water quality. This escalating issue has become a concern and requires strategic technology deployment to address the threat. In this view, the present work deals with the synthesis of corundum-structured and octahedral site-engineered Mg3- xAxTeO6 (A = Fe, and Co; x = 0. 05-0. 25 wt. %) pigments with brilliant colors via a solution combustion route. The designed corundum-structured Mg3- xAxTeO6 pigments exhibit an isostructural geometry with a centrosymmetric space group (R 3 ¯ {{R₃}}). The prepared pigments exhibit aesthetically pleasing and vibrant brown and purple hues through the engineering of site-specific (Mg/Fe/Co) O6 octahedral positions within the corundum-structured Mg3TeO6 lattice. The colors of the pigments were manipulated (i. e. , from absolute white to brown and purple colors) by integrating specific concentrations of transition-metal chromophores. The prepared best-performing Mg2. 85Fe0. 15TeO6 and Mg2. 85Co0. 15TeO6 pigments showcase their capability of delivering exceptional average reflectance properties in the near-infrared region (800-2500 nm) of ∼86%. The integration of transition-metal ions into corundum-structured Mg3TeO6 could effectively modulate its electronic structure through hybridization between O (p) and Fe (d) /Co (d) states, thereby enhancing the near-infrared reflectance of the pigments. The prepared pigments delivered a low thermal conductivity of about 0. 06 and 0. 08 W/m. K, which signifies their candidacy in cooling systems over traditional roofing materials. The cooling pigments demonstrated their stability against acid/alkali treatment, photo-resistivity, and thermal stability. The deficient electricity demand as compared to bare cement and TiO2-mica pearlescent pigment coating was evidently witnessed when the prepared pigments were used as cool coatings in an energy simulation. All clarifies the suitability of pigments in real-time implementation.
Darshan et al. (Sun,) studied this question.