Structural evolution of transition metal orthoborates (Zn3B2O6-Co3B2O6) with the Kotoite mineral structure: Synthesis, structure and properties

We describe the synthesis, structure, optical, magnetic, and dielectric properties of Zn3B2O6 and Co3B2O6 systems with the detailed investigation of the structural transition along with the evolution of color. The compounds (Zn3-xCox)B2O6 (0 <= x <= 3) were synthesised by high temperature solid-state reactions. Rietveld refinements of the powder X-ray diffraction (PXRD) patterns on (Zn-2.25 Co-0.75)B2O6 and (Co2.25Zn0.75)B2O6 samples indicate uniform distribution of Zn and Co in their respective crystallographic sites. UV-Vis absorption spectra on the samples can be explained based on the electronic transitions of Co2+ ions in tetrahedral and octahedral coordination. NIR reflectivity studies on Zn3B2O6, was found to be better than that of TiO2, which suggests possible use of this compound for reflective coatings. The temperature dependent magnetic susceptibility studies indicate antiferromagnetic behaviour. The compounds exhibit low dielectric loss across the investigated frequencies.

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In this study, the synthesis, structure, optical, magnetic, and dielectric properties of Zn3B2O6 and Co3B2O6 systems were investigated. The compounds exhibited distinct features in structural transition and color evolution. It was found that Zn3B2O6 showed superior NIR reflectivity compared to TiO2, and the compounds showed good magnetic behavior and low dielectric loss.