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

Abstract We describe the synthesis, structure, optical, magnetic, and dielectric properties of Zn 3 B 2 O 6 and Co 3 B 2 O 6 systems with the detailed investigation of the structural transition along with the evolution of color. The compounds (Zn 3‐x Co x )B 2 O 6 (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 )B 2 O 6 and (Co 2.25 Zn 0.75 )B 2 O 6 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 Co 2+ ions in tetrahedral and octahedral coordination. NIR reflectivity studies on Zn 3 B 2 O 6 was found to be better than that of TiO 2 , 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.